fix configure.ac help string
add Google Test skelton code
fix README.md
split .gitignore for examples
fix `is_near_lt` and `is_near_gt` issue on zero
move and add tests for Base64 and digest_blocksize
make more template for digest types checking code
set fixed parameters for small tests
remove unnecessary type_traits
add assertion for blockhash_comparison class

This commit restricts the use of existing functions
(s1len and s2len must be at least big as min_match).
add more Base64 tests (locale dependent!)
fix is_safe_for_score_cap
add implicit static_assert to clarification
add score capping tests
bump version to 3.0-rc7