conversions to global atoms
- enhanced internal handle <=> pointer conversions, as well as
  validity of such objects (life time, destruction, mutual access...)
- fixed a few ANSI/Unicode issues, stores most of the data as Unicode
- started having both Ansi/Unicode DDE window procs for message A/W
  transformation
- fixed a few segmented pointer issues (mainly in DdeInitialize &
  DdeGetData)
- added most of the CBF_ flags handling
- implemented the conversation announcement (XTYP_CONNECT_CONFIRM) on
  server side
- enhanced DdeQueryConfig and implemented DdeReconnect
- implemented conversation termination (including XTYP_UNREGISTER)
- several others code clean up
- added transaction support on server side too