refactor static assert queries
refactor context_hash related classes
refactor rolling_hash related classes
comment on existing doubtful behavior in an example
change default settings in an example
add Base64 tests
fix isbase64 function to handle plus and slash as Base64 chars
add digits_in_decimal tests
fix digits_in_decimal issue by adding template parameter
add digest_blocksize tests
refactor digest_blocksize class
refactor string utilities
simplify assertions in digest.hpp
refactor digest-related classes
bump version to 3.0-rc6