JGit commit objects are a recursive data structure; they have links to
their parent commits. Serializing a JGit commit will try to recursively
serialize all reachable ancestors as faras they have been loaded. If
that ancestor chain is too long, a StackOverflowError is thrown during
Wicket's page serialization if a page has a reference to sucha JGit
commit.

Fixed by making sure that pages o not contain references to JGit
commits. Use the (existing) wrapper object RepositoryCommit instead.

* RepositoryCommit has a transient reference to the JGit commit and
  reads the commit from the repository upon de-serialization.
* RefModel is a similar case (JGit tags/branches may also have links
  to the commits they point to). Solved a bit differently by making it
  a pure data object by transferring the interesting data from the JGit
  object in the constructor.
* Change DataViews instantiated with RevCommit to use RepositoryCommit
  instead.
* Change inner anonymous DataViews to ensure they do not have a
  synthesized field referencing the "allRefs" map. Such a synthesized
  field would also get serialized, and then serialize JGit commits
  again.
  
Finally, remove non-transient logger instances in Wicket classes. Those
might lead to NotSerializableException.

These StackOverflowErrors have been reported in several places since
2014:

* https://groups.google.com/forum/#!topic/gitblit/GH1d8WSlR6Q
* https://bugs.chromium.org/p/gerrit/issues/detail?id=3316
* https://groups.google.com/d/msg/repo-discuss/Kcl0JIGNiGk/0DjH4mO8hA8J
* https://groups.google.com/d/msg/repo-discuss/0_P6A3fjTec/2kcpVPIUAQAJ
* https://github.com/gitblit/gitblit/issues/1011
* https://github.com/tomaswolf/gerrit-gitblit-plugin/issues/21

Due to a wrong comparison, when loading the preferred locale in the
user preferences page, in cases like `zh_CN` or `de_DE` the wrong
locale would be chosen.

As with too many things, the code is duplicated on the `UserPage`
and the `EditUserPage`. And they differ. So extract the choosing of
the preferred language for display into a method in the (more up-to-date)
`UserPage` and call that from the `EditUserPage`.

If, for example, an external site links to a docs page or a specific
doc page, and the branch that link points to is no longer existing,
an internal error happens due to a NPE.

The NPE is guarded against and a No Docs page is returned.

Integrate the `PasswordHash` class and subclass in the user
and password editing and authentication. Replaces the old code and
the previous `SecurePasswordHashingUtils` class.

This reverts commit c3e317a288.
Was added by mistake here. Should go into own branch to be able to merge with upstream using separate PR

if key is empty of can not be parsed, form did provide any feedback to
user before

Update the link target to the query parser syntax page of the 5.5 version.

Refactor the `LuceneSearchPage` to use an `ExternalLink` for the link
to the lucene page, so that the link target is kept and updated in the
Java code. Move the link out of the language files. This was way too
cumbersome to update the link target (which is probably why no one ever
did).

The query help text is changed to contain a variable:
`gb.queryHelp = here be some ${querySyntax} help`, which is replaced by
Wicket with a link.
The link text is a new lange file property: `gb.querySyntax`.

Addresses #1166

Disabled links in the PagerPanel (used on the LuceneSearchPage to page
through search results) were only rendered as "disabled". The links
themselves remained active, which gives strange effects when clicked.
For instance it was possible to move to result pages -1, -2, and so on.

Really disable the links. Add missing CSS rules to have correct styling
as Wicket renders disabled links as spans, not anchors. Include the new
CSS file in BasePage.html. And add the left/right arrows only if not on
the first/last page.

The merge type is a per repository setting. Add it to the edit page.

Add the option to merge a ticket branch to the integration branch
only when it can be fast-forwarded, or
always with a merge commit, or
by fast-foward if possible, otherwise with a merge commit.

Adds a new property ticket.mergeType with the valid values
FAST_FOWARD_ONLY, MERGE_ALWAYS and MERGE_IF_NECESSARY.

Merging and canMerge were refactored to make use of a new
IntegrationStrategy class for each type of strategy.

+ Supports referencing:
  + Tickets from other tickets via comments
  + Tickets from commits on any branch
+ Common TicketLink class used for both commits and tickets
  + TicketLink is temporary and persisted to ticket as a Reference
+ Support deletion of ticket references
  + Rebasing patchsets/branches will generate new references
  + Deleting old patchsets/branches will remove the relevant references
+ Substantial testing of use cases
  + With and without patchsets, deleting, amending
  + BranchTicketService used during testing to allow end-to-end ref testing
+ Relocated common git helper functions to JGitUtils

+ Prevent Edit of old doc version

+ New docEdit page with links from docPage and docList
+ Bespoke menu system with full screen edit mode
+ npm required for building client side scripts
+ Ant script added for BuildUI which performs npm commands
+ Update font-awesome to 4.5.0
+ Factor out to JGitUtils common code in BranchTicketService for EditFilePage
	+ getTreeEntries
	+ commitIndex
+ Merge capability for document editing

+ View and Raw both download the actual file
+ Blame will show the metafile

+ GitLFS client support
+ FilestoreModel now parses meta file
+ Read meta heading from cache if available
+ Authentication based on accept headers for browser view filestore login
+ PathModel & PathChangeModel now understands filestore items
+ Zip & Rar downloads contain include filestore items
+ Filestore servlet returns LFS JSON error only if accepted by client
+ DiffStat now knows repository to allow identification of filestore items
+ Filestore items identified and returned via view, raw & blob links on
blame, commitDiff, commit and Tree pages

+ JS patch/hack to coerce legacy wicket into talking to a HTML5 input type
+ JS script to hide inline help on date format when using HTML5 date picker
  + Date picker shown in user locale and standard does not support custom
  format.
  + Always sent in ISO8601 format

+ Filestore listing filtered by user view permissions
+ Configuration help for filestore relocated to website files
+ Added migration example

+ Adds standard logging for all authentication providers
+ Updates help page to use default GitBlit SSH port

+ Metadata maintained in append-only JSON file providing complete audit
history.
+ Filestore menu item
	+ Lists filestore items
	+ Current size and availability
	+ Link to GitBlit Filestore help page (top right)
+ Hooks into existing repository permissions
+ Uses default repository path for out-of-box operation with Git-LFS
client
+ accessRestrictionFilter now has access to http method and auth header
+ Testing for servlet and manager