Refactor EditorDiffMargin.UpdateDiffDimensions to simplify visibility handling
Remove unnecessary code duplication
Duplicate UpdateDiffDimensionsImpl in preparation for separate handling of removed blocks
Simplified code for handling "normal" hunks
Simplified code for handling "deleted" hunks (fixes #44)
Fix incorrect handling of submodules
Perform required argument check before calling Repository.IsValid
Do not create custom margins for files not located in a Git repository
Prevent ScrollDiffMargin from affecting the scroll bar behavior
Merge pull request #49 from sharwell/no-hit-test

Prevent ScrollDiffMargin from affecting the scroll bar behavior
Add support for Visual Studio 14 CTP
Merge pull request #50 from sharwell/play-nice

Play nice with other source control providers
Merge pull request #51 from sharwell/submodules

Fix incorrect handling of submodules
Merge pull request #48 from sharwell/fix-44

Improved editor diff positioning
Merge pull request #55 from sharwell/vs14ctp

Add support for Visual Studio 14 CTP
Add a VSPackage to the project (required for menu commands and options pages)
Define toolbar commands for the Git Diff Margin actions
Use IVsToolbarTrayHost to provide the toolbar functionality