With modification on /usr/include/g++/cmath (search PATH issue, see TODO), it is now packaged.
- PLIST update
- Remove self package from CONFLICTS+=
- Remove already .if 0 ... .endif clause
- Add REPLACE_PYTHON files onto TODO
- Correction of versions on buildlink3.mk
- Add two lines on Makefile
  +BUILD_DEPENDS+=  ${PYPKGPREFIX}-sphinx-[0-9]*:../../textproc/py-sphinx
  +DEPENDS+=        ${PYPKGPREFIX}-lxml-[0-9]*:../../textproc/py-lxml/