Basic math.h constants and functions were added. Now when one wants to speedup
the following code::

    from math import sin, cos
    e = sin(5) + cos(6)

one can do::

    from libc.math cimport sin, cos
    e = sin(5) + cos(6)

Not all math.h features are wrapped (yet), but basic functions should work.
Signed-off-by: Ondrej Certik <ondrej@certik.cz>

refactor scope handling in ScopedExprNode, enable type inference for inlined genexpr nodes, fix type coercion of sum(genexpr)

--HG--
rename : tests/run/lambda_module.pyx => tests/run/lambda_module_T603.pyx

setup.py option '--cython-compile-all' to compile more Cython modules during installation than enabled by default

--HG--
extra : rebase_source : 7fea7f050894df69b66a2bdb843ce1885ef7ef7a

really fix parallel/cascaded assignments this time (and test it): make sure the rhs values are evaluated in source code order