portal: combating the space-detection issue. what needs to be tweaked next is how far away objects are spawned. it should either be a trial&error adjustment or depend on the object's moving direction and the portal's angle in order to avoid issues with box collisions. if the spawn distance to the portal is just a fixed value (as it was before this patch) or a constant factor (it is now) it can be too big for "nice" portal angles (in tight gaps with still enough space, but -> denied) and too small for bad angles (box collision esp. on big objects like barrels -> denied)

FIND_PATH(GMP_INCLUDE_DIR gmp.h)

FIND_LIBRARY(GMP_LIBRARY NAMES GMP gmp)

IF (GMP_INCLUDE_DIR AND GMP_LIBRARY)
   SET(GMP_FOUND TRUE)
   ENDIF (GMP_INCLUDE_DIR AND GMP_LIBRARY)

   IF (GMP_FOUND)
      IF (NOT GMP_FIND_QUIETLY)
            MESSAGE(STATUS "Found GMP: ${GMP_LIBRARY}")
      ENDIF (NOT GMP_FIND_QUIETLY)
   ELSE (GMP_FOUND)
   IF (GMP_FIND_REQUIRED)
      MESSAGE(FATAL_ERROR "Could not find GMP")
   ENDIF (GMP_FIND_REQUIRED)
ENDIF (GMP_FOUND)