New CSS linter which is much more powerfull than the previous one.
Configuration is default but I had to remove a few rules that were
throwing too many or weird errors.

More importantly, the linter will exit with code 1 on errors so now our
build will fail if the CSS linter fails which should eliminate linter
errors being introduced without notice.

* Add lang specific font stacks

* Force font changes

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix icons

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Fix octicons and icons

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Just override the semantic ui fonts only

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Missed the headers... override them too

* Missed some more semantic ui stuff

* Fix PT Sans

Signed-off-by: Andrew Thornton <art27@cantab.net>

* More changes

Signed-off-by: Andrew Thornton <art27@cantab.net>

* Squashed commit of the following:

commit 7d1679e907
Author: Mike L <cl.jeremy@qq.com>
Date:   Wed Mar 13 13:53:49 2019 +0100

    Remove missed YaHei leftover from _home.less

commit 0079121ea9
Author: Mike L <cl.jeremy@qq.com>
Date:   Wed Mar 13 12:03:54 2019 +0100

    Fix overdone fixes (inherit, :lang)

commit 62c9199159
Author: Mike L <cl.jeremy@qq.com>
Date:   Wed Mar 13 02:29:10 2019 +0100

    Fix elements w/ explicit lang (language chooser)

commit b3117587aa
Author: Mike L <cl.jeremy@qq.com>
Date:   Tue Mar 12 20:17:26 2019 +0100

    Fix textarea also (to match body)

commit 81cedf2c30
Author: Mike L <cl.jeremy@qq.com>
Date:   Tue Mar 12 19:41:39 2019 +0100

    Revert css temporarily to fix conflict

commit 80ff82797f
Author: Mike L <cl.jeremy@qq.com>
Date:   Tue Mar 12 19:15:30 2019 +0100

    Tweak CJK, fix Yu Gothic, more monospace inherits

commit 581dceb9a8
Author: Mike L <cl.jeremy@qq.com>
Date:   Mon Mar 11 13:09:26 2019 +0100

    Add Lato for latin extd. & cyrillic, improve CJK

* update stylesheet

* Allow markdown table to scroll

`overflow:auto` isn't effective when a table is wider than the container. Adding `display:block` fixes this issue.

Signed-off-by: Andrew Boyarshin <andrew.boyarshin@gmail.com>

* Markdown rendering overhaul

Cleaned up and squashed commits into single one.

Signed-off-by: Andrew Boyarshin <boyarshinand@gmail.com>

* Fix markdown API, add markdown module and API tests, improve code coverage

Signed-off-by: Andrew Boyarshin <boyarshinand@gmail.com>

This does not change any content and generated gogs.css is still the same.

- copy link button: #1396, #1168, #1668,
- synxtax highlight: #1712, #1549, #1315, #670
- z-index: #1942

- conf/locale: add mew translator profile