1.5.1: Fix Python 3.7 compatibility, improve caching
- Fixed Python 3.7 compatibility (scanf_compile broke in 3.7 due to differences in re.sub)
- Changed caching to functools.lru_cache for Python 3, backports.functools_lru_cache for Python 2.7 (thanks @eendebakpt!)
- Caching now takes collapseWhitespace into account (thanks @prittenhouse!)