Fix initialization of IProject.TypeDefinitionModels.
Add 'SD.MainThread.InvokeAsyncAndForget()' method that combines 'InvokeAsync().FireAndForget()' into a single step.

This makes debugging SharpDevelop easier because exceptions are left unhandled; they don't get caught by a Task<T>.
Implemented ITypeDefinitionModel.NestedTypes.
Replace DelegateCommand and DesignCommand with RelayCommand.
Don't serialize InternalBreakpointObject.
Use InvokeAsyncAndForget() instead of InvokeAsync().FireAndForget().
Fix crash when opening load/save options panel.
Fix crash when running Find References while a .xaml file is open.
Use the unresolved member to check that the stack-frame is valid.
Removed some debugger options
Re-write debugger options to use accessors with Get/Set methods.
Fix broken unit tests due to last commit
Missing Text in Debugger.AddIn/Options/DebuggingSymbolsPanel.xaml.cs
Add WiX addin.

WiX dialog designer is currently disabled.
Sub menu items for the context menu in setup files view are disabled
since the ISubmenuBuilder no longer exists.
implemented more methods in CSharpCodeGenerator + Tests and added back SuppressMessageCommand
Add Package Management addin.

PowerShell console disabled.
Running PowerShell scripts on install/uninstall of a NuGet
package is disabled.
Refactored handling of debug symbols
Fix evaluation bug caused by null from GetArgumentValue
Add code coverage addin.

Extended TestExecutionOptions to allow post processing of the
NUnit ProcessStartInfo.
Drop down button in Code Coverage pad is not working.
Commented out some unit tests and code temporarily.
Convert SettingsEditor to Wpf