- Added SpawnDecal ACS function:
    int SpawnDecal(int tid, str decalname, int flags, fixed angle, int zoffset, int distance)
  Traces a line from tid's actor until hitting a wall, then creates a decal there. Returns the
  number of decals spawned.
  * tid = Which actor(s) to start the trace at.
  * decalname = Which decal to spawn.
  * flags =
    * SDF_ABSANGLE = Angle parameter is an absolute angle. Otherwise, it's relative to the origin actor's angle.
    * SDF_PERMANENT = Decal ignores cl_maxdecals. Otherwise, it will eventually disappear.
  * angle = Direction in which to search for a wall. Defaults to 0.0.
  * zoffset = Offset from the middle of the origin actor for the Z height of the decal. Defaults to 0.
  * distance = Maximum distance to search for a wall. Defaults to 64.

git-svn-id: http://mancubus.net/svn/hosted/zdoom/zdoom/trunk@4330 a95907f1-e10c-0410-b46f-9e587ccb1026