More thorough GF256 tests and one resulting fix.

pow(0,p) for p > 0 was returning zany results - the idea of encoding a
second half of ALOG_TABLE with zeros cleverly saved a test for zero in
mult, but relies on the log value staying >= 512 which it can't in pow
after p*...%255. Simplest fix is to add a test.
Merge branch 'stricter-GF256-tests' of https://github.com/jcflack/archistar-smc into jcflack-stricter-GF256-tests
Merge branch 'jcflack-stricter-GF256-tests'
fix whitespaces