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.
- 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.
- 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.