Don't abort when merely checking if a non-map is a map

- When P_OpenMapData() is called by P_CheckMapData(), we don't actually
  care if any required lumps are missing. This just means it isn't a valid
  map, so don't abort with I_Error().
Don't abort for TEXTUREx lumps that define textures with no patches

- A texture defined in TEXTUREx without any patches isn't necessarily an
  error, so accept. This also means they shouldn't be used for determining
  if a TEXTURE directory belongs to Strife instead of Doom.
Merge branch 'maint'
- removed all uses of single precision floats from FraggleScript code.
Fixed compilation with LLVM compilers
Merge branch 'master' of https://github.com/MazterQyou/zdoom
- fixed: Cost strings for dialogues must not be added in the dialogue parser but while displaying the message to properly handle stringtable entries.
- fixed: displaying sprites on the automap ignored both the actor's scale and translation.
Merge branch 'maint'
- fixed: The Hexen bridge must make its balls disappear when it gets destroyed.

Hexen did this with a call to A_BridgeRemove in Thing_Destroy which merely set a flag in the bridge object, which cannot be done safely in ZDoom because it's not guaranteed that the ball object calls A_BridgeOrbit and the garbage collector may delete the bridge actor before it can be checked so now the Bridge's Destroy method deletes all balls attached to the bridge object itself.
Merge branch 'maint'