Quoter

Added ``but`` synonym for ``clone`` to have simpler, clearer
invocations.

Docs were getting long. Truncated ``README.rst`` and converted
majority to Sphinx docs to be hosted on readthedocs.

Documentation fix.

Major rewrite of complex argument handling for XMLQuoter (and
HTMLQuoter subclass). Should be much more robust and extensible.
Refactored some functions into ``util.py``

Adds direct attribute setting ``[key=value]`` to the CSS selector
specification language.

Improved testing. Added new tests of sub-cases of parsing the
arguments. Updated strategy to have quicker basic tests with
``sudo tox``, but easy full coverage analysis with ``sudo tox -c
toxcov.ini``. Advances test line coverage to 100%.

Updated testing strategy with integrated multi-version coverage
testing. Achieved 98%.

Fixed RST problem in docs