Unlike clang, VS didn't like me using the value of one 'static const'
integer variable to compute the value of another, and complained
'initializer is not a constant'. Replaced all those variables with an
enum, which should also more reliably ensure that even an
unsophisticated compiler doesn't actually reserve data-section space
for them.
A new module in 'utils' computes NFC and NFD, via a new set of data
tables generated by read_ucd.py.
The new module comes with a new test program, which can read the
NormalizationTest.txt that appears in the Unicode Character Database.
All the tests pass, as of Unicode 15.
