* for pull request #258: update CHANGES, add tests, add a document and refactoring.

--HG--
rename : tests/roots/test-tocdepth/conf.py => tests/roots/test-directive-code/conf.py
rename : tests/roots/test-tocdepth/index.rst => tests/roots/test-directive-code/dedent.rst
rename : tests/roots/test-tocdepth/index.rst => tests/roots/test-directive-code/index.rst
rename : tests/root/literal.inc => tests/roots/test-directive-code/literal.inc