-add standard QUIET and REQUIRED handling
-add GIF_LIBRARIES variable as readme.txt says
-add name giflib to the names for the gif library
-remove some unnecessary search paths for the lib (they are already part of
the standard search paths, see Modules/Platform/UnixPaths.cmake)
-FindFreetype.cmake: use PATH_SUFFIXES include again for the headers with
the CMAKE_PREFIX_PATH variable

Alex