TreeView expansion, Fact/Or options in NPTPNE, nodes name validation, pns' initialization.

-> Made ProjectView(TreeView widget) expand when window is resized.
-> Added Fact, Structured Fact and OR places options for context menus in NonPrimitiveTaskPNEditor.
-> Added some name validation.
  '-> Made name validation method private in nodes.
  '-> Added a couple of regex to validate fact names.
-> Edited PNs' _initialize methods.
  '-> Renamed default transitions: Preconditions and Rule transitions are named just like their classes.
  '-> Added code to _initialize method for FinalizingPN.