python-sage: move files around, turn into templates

(this is to help git keeping track)
python-sage: gen_interpreters.py, add main
move module bounds to configuration.

(also, get rit of duplicate stdint.h)
python-sage: build system

- BLAS, BLAS2 check
- generate setup.py, module_list.py (useful?)
- AC_ARG_VAR...
- am_check_python_headers
- AM_DEFAULT_EXT globally (?)
- common makefile
  - dependency tracking for cython files
  - some automake global flags
  - some recursive targets
- add all makefiles to AC_OUTPUT
- header checks
  - cliquer/cl.h
  - flint
  - libgap
  - ..
- create dependency dummies for cython
- AC_AUTO_HEADER (reduce cruft in gcc-calls)
- checks
  - jinja2
  - whether cython supports dependencies
  - cliquer/cliquer.h
python-sage: Makefiles
Merge branch 'stdint' into python_sage_build

Conflicts:
	src/sage/module_list.py.in (pyx vs pyxx...)
python-sage: module_list

- BLAS
- conditional extensions
- include paths
- m4ri extra_compile_args
python-sage: .gitignore update
python-sage: env.py
python-sage: remove sage-location check

- the check involves hardwird SAGE_LOCAL
- sage-location is no longer used to fix ipython
python-sage: various references to SAGE_DOC_SRC
python-sage: __file__ doctest issues

adding explicit __file__ (for VPATH builds) in doctest changes result
slighly

hmm probably this is not a problem.
python-sage: sage-started, will not work like this

SAGE_ETC might be not writable at run time. maybe fallback to SAGE_DOT?
python-sage cython.py repair explicit CSAGE_INCLUDEDIRS

(why does cython py not just take CPPFLAGS fom env?!)
python-sage: whitelist python2.7 multiprocessing in stackframes test
python-sage: comment on header hack
python-sage: make libgap obsolete (I)
python-sage: make libgap obsolete, II (patches against gap upstream)
python-sage: fix sage_getfile (still needed?)

sage_getfile is expected to return the absolute path to the *source*
file. inspect.getabsfile returns the path to the compiled object, if
it's not in the same direcory.
pkgconfig package, incomplete