implemetation of loop unrolling suggested in #37; various changes to reuse buffer, write to TextWriter, and handle int.MinValue; speed hasn't been tested yet
speed test for #37; it's slower, but the existing write it code has been improved since the issue was opened; need to apply TwoDigits optimization and compare again
convertng #37 to TwoDigit form; it's about 10% faster
rename to remove I37 for things
same optimizations for uints
same optimization for longs; gonna need a test for these since doubling the # of branch points isn't exactly a no-brainer
same optimizations for ulongs
test that unrolling is faster for longs; it's not, which makes some since since it's literally double the number of branches
remove long unrolled versions; this ints are where the gains are; closes #37