An update of platforms HexenC code from Thomas Freundt.  Originally, the
intention was finding a way of making the elevator in egypt1 leading to
the boss-level exit to behave:  that "ankh platform" isn't user friendly
because you have to make a timely jump to go past it.  The code was then
improved for compatibility into the current form.

Quoting Thomas:

 "As I wanted to have the improved functionality with the remaining
  platforms as well, I looked at all other platforms that are
  initialized by func_plat.  Their mode of operation appears more
  reasonable with deathmatch (ravdm5) than in levels mainly designed
  for single player.  Only the ankh platform has self.wait defined, but
  the original code ignores this field.
  Therefore, I wanted my amendments to meet the following requirements:
  - full savegame compatibility (new progs with old savegame
    && old progs with new savegame)
  - no modifications to entity files
  - special treatment of the ankh platform
  - similar more user friendly behaviour of the other platforms
  - close to original behaviour during deathmatch / teamplay
  I have commented the important parts; as usual.  ..."


May need some more testing before including mainstream.

