fix a bug that causes monsters to become partly invisible

when walking inside liquids like water -- on big-endian systems

Originally reported by Ronald Lasmanowicz and fixed in his
wii-hexen port: https://code.google.com/p/wii-hexen/source/detail?r=17
fix some more endianess issues with the width fields in patch_t structs

as pointed out necessary by Ronald Lasmanowicz for his Wii ports
Merge branch 'master' of https://github.com/chocolate-doom/chocolate-doom