Updated references to xwt, md-addins
[MSBuild] Fix getting project references on .NET
[Ide] Fix error cleanup issue

When there is an unexpected exception building a project the object source
(the solution) was not set, so the error was not cleared when closing
the solution.

Fixes bug #20687 - The error message should be cleared when we close a solution
[Ide] Fix stock icon loading issue

Don't preload stock icons until all icons have been defined.
[Ide] Fix icons in find in files dialog

Fixes bug #20041 - Incorrect size of icons
[Ide] Fixing disabled OSX ContextMenus in Modal dialogs(Bug 20683)
Merge pull request #598 from DavidKarlas/bug20683m

[Ide] Fixing disabled OSX ContextMenus in Modal dialogs(Bug 20683)
[Ide] Fix crash when opening context menu

... when using the keyboard shortcut.
[Mac] Properly enable/disable menu items
[Mac] Fix previous commit
Updated reference to md-addins
[Ide] Fix minor assembly resolution issue

Use the active configuration when getting the referenced assemblies to be used
for code completion.
[Ide] Add support for cross-toolkit images

Xwt.Drawing.Image objects can now reference native images from different
toolkits. For example, a single Image object can contain a reference
to a Gdk.Pixbuf and an NSImage. The goal is to be able to use a single
object instance to represent an image that can be rendered in any
supported toolkit.

ImageService now loads the icons using a special api that allows
specifying the image source. This source will be used to load
platform-specific images on demand.
[Ide] Added Control class

Also added mac-specific build configurations that conditionally
reference MonoMac.
[Ide] Rename __MAC__ to MAC
Updated reference to md-addins
Run tests with `-labels` so hangs are easier to diagnose.
[Core] Fix project reloading issue

The ReloadItem method now takes into account that the Items list may have
changed while loading the new instance of the project. It may happen for
example if the project is migrated and that causes a file save, and that
causes a reload.

This fixes bug 20615 - XS throws exception on migrating MonoMac project
to XamMac through Projects-> Migrate to Xamarin.Mac
Merge pull request #600 from mono/xplat-ui

Initial work to support platform-specific UIs
[Ide] Fix memory leak when reloading solutions