When a commit is blamed for multiple lines of the result file the
command line interface prints the same text before each line in that
span.  Format these strings once and reuse them as the line prefix.

For long files (e.g. 2425 lines of ReceiveCommits.java in Gerrit)
this can save as much as 20ms during the output phase of the command
line blame program.

Change-Id: Ie42787d77c8d0cbca7ccbf59c795120494a2a891

Ensure commit object names are unique by extending the default
abbreviation as long as necessary. This allows `jgit blame` to
more closely match the formatted output of `git blame` on large
histories like Gerrit Code Review's ReceiveCommits.java file.

Change-Id: I5f7c4855769ee9dcba973389df9e109005dcdb5b

The change includes comparing symbolic links between disk and index,
adding symbolic links to the index, creating/modifying links on
checkout. The behavior is controlled by the core.symlinks setting, just
as C Git does. When a new repository is created core.symlinks will be
set depending on the capabilities of the operating system and Java
runtime.

If core.symlinks is set to true, the assumption is that symlinks are
supported, which may result in runtime errors if this turns out not to
be the case.

Measuring the cost of jgit status on a repository with ~70000 files,
of which ~30000 are tracked reveals a penalty of about 10% for using
the Java7 (really NIO2) support module.

Bug: 354367
Change-Id: I12f0fdd9d26212324a586896ef7eb1f6ff89c39c
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

Translatable texts aren't API and shouldn't require maintenance of
@since tags to prevent API warnings.

Change-Id: I228ff37f17c0e792a6bc188c463a0d19138e88ac
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

A few classes such as Constanrs are marked with @SuppressWarnings, as are
toString() methods with many liternal, but otherwise $NLS-n$ is used for
string containing text that should not be translated. A few literals may
fall into the gray zone, but mostly I've tried to only tag the obvious
ones.

Change-Id: I22e50a77e2bf9e0b842a66bdf674e8fa1692f590

Invoke the wrapper types' valueOf via static imports.
For booleans used in asserts, add a new assert in
the JUnit utility package since out current version of JUnit
does not have the assert(boolean, boolean) method.

Change-Id: I9099bd8efbc8c133479344d51ce7dabed8958a2b

The underlying problem is that System.out is a PrintWriter and
as such it does not throw exceptions on error, but rather just
sets a flag and continues.

This changes replaces the use of System.out with a PrintWriter-like
writer that does not catch error, but instead throw them to the
caller.

Bug: 366243
Change-Id: I44405edc4416e943b87f09a0f6ed041c6c51b046

Command line options match the C implementation of `git blame` as
closely as possible, making for a pretty complete tool.

Change-Id: Ie1bd172ad9de586c3b60f0ee4a77a8f047364882
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>