0.30

• All methods that have default arguments in Godot, now have default
  arguments in SwiftGodot - there are no longer any exceptions (Miguel)

• Fix the PropInfo that is generated for exported function parameters
  and returns, to produce better live documentation in Godot (Estevan
  Hernandez)

• Diagnostics: Assert in class initialization, to indicate that you
  have not registered the class for use (@pcbeard, Miguel)

• GD.printDebug helper method that prints into the Godot debug window
  the line and number of the error, similar to the function in
  GDScript (Estevan)

• Locking of internal tables, to allow Swift/Godot objects to be
  properly tracked in multi-threaded environments (Miguel)