Convert doctests to unit tests in 'containers'.
Convert doctests to unit tests in 'date'.
Convert doctests to unit tests in 'misc'.
Convert doctests to unit tests in 'number'.
Split multiple asserts to separate tests.
Delete Unicode u'' test; not Python3 3 compatible.
Convert doctests to unit tests in 'text'.
image() no longer accepts args 'path' and 'use_pil'.

These args invoked the WebHelpers 'media' package which was not ported to
WebHelpers2.
Document that 'html' doctests are not converted.
Change series() argument signature.