provide SAGE_DOC_SRC environment
fix qepcadrc path
don't rely on $SAGE_LOCAL/bin/python.
python-sage: various references to SAGE_DOC_SRC
cython.py: don't rely in $SAGE_LOCAL
unhardwire sage-CSI
python-sage: remove sage-location check

- the check involves hardwird SAGE_LOCAL
- sage-location is no longer used to fix ipython
Merge branch 'runtime_paths' into python_sage_build
python-sage: env.py
python-sage: cython.py repair explicit CSAGE_INCLUDEDIRS

(why does cython py not just take CPPFLAGS fom env?!)
python-sage: .gitignore update
Merge branch 'doc_src' into python_sage_build
libfplll: sanitize includedir
Merge branch 'fplll' into python_sage_build
libgap package: put headers into $pkgincludedir
change references to libgap/*.h
bump libgap package patchlevel
Merge branch 'libgap_include' into python_sage_build
initialize SAGE_ETC (from environ) in sage-location before use
close parenthesis