bump md-addins for Xamarin.Mac regression fix
[Ide] Fix typo in internal API names
[Ide] Fall back to parser for base mimetype
[Xml] Fix code folding for custom XML filetypes
Update gitignores
[Xml] Code cleanup in XML addin

Removed lots of unnecessary/incorrect asserts too
[Xml] Fix code completion failure after backspacing

BXC16950 - (IntellisenseBug) Intellisense in code editor stops working
after 4th element/view in a .axml file

When backspacing or moving the caret backwards, the code completion
engine take a shortcut. Instead fo reparsing the entire file, it
clones the parser stack at a known good position before the cursor,
and reparses up to the cursor.

The problem was that cloning was not cloning the attributes. This meant
that completion for namespaced attributes failed because it did
not find the xmlns:foo on the parent element.
[TextEditor] Avoid unnecessary calls to GdkWindow.Cursor
[Refactoring] FindDerivedSymbolsHandler no longer blocks the UI
thread.
bumped debugger-libs for iOS debugger fix
Updated references to xwt, md-addins
[Ide] Add new PlatformService.OpenTerminal variant

It supports setting the window title and environment variables.
[Core] Add explanatory comment for a hack
[Windows] Implement PlatformService.OpenTerminal
[MSBuild] Builder interface library doesn't need to be an x86 exe

Make it an AnyCPU library to fix warnings and prevent executing it.

Assembly identity is still the same.
[MSBuild] Add assembly redirects to v12 builder
[MSBuild] Reorganize the builders' assembly redirects
Fixed 'Bug 17277 - Code analysis having problems with corelib'.
[Ide] GetCacheDirectory has now a more fine grained locking strategy &
only touches the cache on first access.
[Core] Fix all the warnings