Track api changes
[Ide] Add missing 2x icons
Bump md-addins
[Ide] Make rendering of welcome page icons retina aware
[Icons] nunit-overlay-32.png → project-nunit-overlay-32.png (and a new icon)
[Icons] New component icons (cube instead of a plug)
[Icons] md-addins bump
Remove language overlay from the project icons
[Icons] project-gui-32.png → project-gui-overlay-32.png (and a new icon)
Merge remote-tracking branch 'origin/master' into retina

Conflicts:
	main/external/xwt
	main/src/core/MonoDevelop.Ide/MonoDevelop.Components/GtkUtil.cs
	main/src/core/MonoDevelop.Ide/MonoDevelop.Ide.WelcomePage/WelcomePageRecentProjectsList.cs
	version-checks
Bump md-addins
[Icons] empty-file-32.png → file-generic-32.png (and a new icon)
[Icons] Updating older icons to current versions
[Icons] New class file icon
[Icons] New interface file icon
[Icons] New struct file icon
[Icons] New enumeration file icon
[Icons] New XML file icon
[Icons] text-file-*.png → file-text-*.png (and a new icon)
[Icons] template-16.png → file-template-16.png (and a new icon)