Update latest v2

[tznind]

Breaking Change Notes

• Mouse button variables renamed
• AllowsTab and AllowsReturn renamed
• Mouse position is now nullable
• Drivers have been renamed (no longer v2 / v2win)
• Slider is now LinearRange

Progress

• Get solution to build
• Get editor to launch
• Right click add label to work
• Set text to work
• Save and reload to work
  • Hello world label
  • Showcase Menu
  • Showcase Tabs
• Get tests to build

Blockers

• PopoverMenu crashes when calling MakeVisible Terminal.Gui#4488

• Toggle is on by default and is horrible (TableView) Terminal.Gui#4485

• MenuBar totally broken with new changes

• SpinnerView crashes on load

Global Exception
Object reference not set to an instance of an object.
   at Terminal.Gui.Views.SpinnerView.<AddAutoSpinTimeout>b__39_0()
   at Terminal.Gui.App.TimedEvents.RunTimersImpl()
   at Terminal.Gui.App.ApplicationMainLoop`1.IterationImpl()
   at Terminal.Gui.App.MainLoopCoordinator`1.RunIteration()
   at Terminal.Gui.App.ApplicationImpl.RunLoop(IRunnable runnable, Func`2 er
rorHandler)