Initial commit of the Sphinx documentation source.

Initial commit of the Sphinx documentation source.
One can build Sphinx documentation set in the html format by calling:
sphinx-build sourcedir builddir

For example:
sphinx-build ./rst_source /tmp/build

Note: This commit does not include the "Complete Reference - API and datatypes". This results into partial disabling of the function cross-referencing enhancement in the generated documentation.

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@24981 dc483132-0cff-0310-8789-dd5450dbe970