test_typecheck_decorator.py: Fixed three overly specific error message tests, they were wrong if file was called via import
README.rst: Made markup PyPI-compatible
setup.py: replaced README.txt with README.rst, added topic descriptors
README.md: now mentions custom predicate generators and threecheck
setup.py: added post-install autotesting
renamed either_value to enum and either_type to any
renamed 'matches' to 'has', introduced 'all' and 'none': Version 0.3b
setup.py: changed development status indicator from "3 - Alpha" to "4 - Beta"