So far, only a flat list of form names was implemented (by far the majority of cases).
Now, hierarchical form names (like "Folder1/Folder2/myForm") are accepted.

Impacts:
- on AllForms() and Forms() collections:
  - insertion of _GetAllHierarchicalNames() to make list of names
  - insertion of _CollectNames(): recursive function to walk thru folders
  - insertion of _GetHierarchicalName(persistent name) to establist correspondence
- on OpenForm action
- on SelectObject action: form windows are not identified by title anymore
- on form and control events
- on arguments check when argument is a form object

Change-Id: I2da73ac3d4fe2d90b2e526fe510207c0f8ec8386