- Separated the linedef activation types into a bit mask that allows combination

of all types on the same linedef. Also added a 'first side only' flag. This
  is not usable from Hexen or Doom format maps though but in preparation of
  the UDMF format discussed here:
  http://www.doomworld.com/vb/source-ports/43145-udmf-v0-99-specification-draft-aka-textmap/
- Changed linedef's alpha property from a byte to fixed point after seeing that
  255 wasn't handled to be fully opaque.
- fixed a GCC warning in fmodsound.cpp 

SVN r954 (trunk)

src/p_saveg.cpp

@@ -356,8 +356,9 @@ void P_SerializeWorld (FArchive &arc)
 	for (i = 0, li = lines; i < numlines; i++, li++)
 	{
 		arc << li->flags
+			<< li->activation
 			<< li->special
-			<< li->alpha
+			<< li->Alpha
 			<< li->id
 			<< li->args[0] << li->args[1] << li->args[2] << li->args[3] << li->args[4];