Bump version to 0.20
version bump
Merge branch 'master' into 0.20.x
Bump version number.
prepare release of 0.19.2
fix release date
add tag for 0.19
minor code cleanups
prepare release of 0.19 beta 2
test 'type_version_tag' directive and fix it in Py2 --HG-- rename : tests/compile/ext_attribute_cache.pyx => tests/run/ext_attribute_cache.pyx