ESM file reading/writing support. Part one.
Use four-char integers in direct (big-endian) ordering.
Use FOURCHAR macro instead of hard-coded ASCII.
Update apps/esmtool/esmtool.cpp, apps/esmtool/record.cpp,
and apps/openmw/mwworld/esmstore.cpp to use four-char integers
in direct (big-endian) ordering.