prefer int over long if there is still 32 bits in int
move operators for split 32-bit implementation into inline functions to not break C90 when using nested operators (subscripting non l-values). whoops.
add last resort check for 64-bit type of unknown size
rename some of the bit counting things to be a bit clearer
documentation update
make md4 and md5 rotation arrays unsigned rather than using the min 32 bit type... gross