Add Xceed.Wpf.AvalonDock.Themes.VS2013.dll to NuGet package
Update AppVeyor links
Update docs to include IMainWindow.

Fixes #83.
Merge branch 'master' of github.com:tgjones/gemini into working
Use [Category] attribute to group inspector editors.

Only used for InspectorBuilder.WithObjectProperties; you can still
completely customise the inspector by adding editors manually. Fixes
#93.
Merge branch 'master' of github.com:tgjones/gemini into working