Editing recent favorite repo list may end up with null repo Path.

Return empty string to prevent from NullArgumentExcaption.
Allow to remove repos with empty Path.
Validate entered commit hash after focus is lost.

Previously user wasn't able to type commit hash by hand.
Changed KDiff3 version
Added a special section for release candidates.

Old GitExt versions will ignore such sections, while new GitExt versions will be able
to properly handle them.
Merge remote-tracking branch 'origin/release/2.48'
Indicate change when repository changed. Closes  #2420.

Partially reverts commit 6e7e6cd4d686d341ce1f703aebb49b4312aeee61.
Merge branch 'release/2.48'
Svn clone prefix fixed
fix GITUI error.png path
fix GITUI StatusHourglass path
fix GITUI success png path
Fix 1st post build event error on GitHub3.csproj

Current Variable $(SolutionDir) yields ../../ path which is wrong
Fix 2nd post build event error on GitHub3.csproj

Current Variable $(SolutionDir) yields ../../ path which is wrong
CONTRIBUTING.md added
Verifying mono version on travis

For debugging purposes only
Adding dummy commands
Fixing nuget.targets folder case for Github3 proj
update NBug ref on TranslationAppMono
update NBug ref on GitExtensionsMono
Merge pull request #2427 from fraga/fixMonoBuild

Fix mono build on travis