CreatePullRequestForm crash fixed. Closes #1727
Support loading dll's from Plugins folder
Show error callstack
Let NBug handle unexpected exceptions
Updated msysgit to 1.8.3
Merge branch 'release/2.44'

Conflicts:
	GitUI/CommandsDialogs/FormBrowse.cs
	GitUI/CommandsDialogs/RepoHosting/CreatePullRequestForm.cs
	GitUI/UserControls/RevisionGrid.cs