Rearchitected stylesheet reading:  - Allow arbitrary nesting, not just one level  - Do not re-read sheets if nesting  - Allow callable objects to be used instead of    filenames (for extension modules)  - Fixed a subtle bug that could cause reporting    of later errors to reference the wrong style    sheet name if a style sheet could not be    located.
Rearchitected stylesheet reading:
 - Allow arbitrary nesting, not just one level
 - Do not re-read sheets if nesting
 - Allow callable objects to be used instead of
   filenames (for extension modules)
 - Fixed a subtle bug that could cause reporting
   of later errors to reference the wrong style
   sheet name if a style sheet could not be
   located.



git-svn-id: 305ad3fa995f01f9ce4b4f46c2a806ba00a97020@1710 3777fadb-0f44-0410-9e7f-9d8fa6171d72

aquavitae/rst2pdf,openpolis/rst2pdf-patched-docutils-0.8,aquavitae/rst2pdf,openpolis/rst2pdf-patched-docutils-0.8,sychen/rst2pdf,tonioo/rst2pdf,tonioo/rst2pdf,aquavitae/rst2pdf-py3-dev,aquavitae/rst2pdf-py3-dev,sychen/rst2pdf