implement generic multi-version dialogs

[westram]

Motivation:

• display multiple (similar) versions of one window, e.g
  • expert/novice
  • simple/advanced (as used by SINA interface)
  • -type dependent settings (see #676)

Features:

• bind window-version to value of an AWAR (eg. to current -type)
• pop up correct window on initial use
• if AWAR changes + window is shown ⇒ change window-version (automatic)
• the window-position of all versions shall be synchronized (esp. on automatic change)

Problem:

• if a pointer to the generated window gets bound somewhere
  (eg. because a CreateWindowCallback is used)
  ⇒ how to change that pointer on version change?