prevent assignment from basestring->bytes, provide better error messages, extend string assignment failures test

extend semantics of 'basestring' typed variables to represent exactly bytes/str/unicode but no subtypes

clean up distutils argument handling in cythonize script, avoid unnecessary cwd changing, move intermediate compiler artifacts into temp directory and delete them afterwards

Allow relative path names for cython freeze.

Fixed IndexNode.is_lvalue

Conflicts:
	Cython/Compiler/CmdLine.py

make fpos_t an opaque type

some missing math.h functions and macros in math.pxd

use -fPIC -shared when compiling "libraries" demo

--HG--
extra : rebase_source : 7b763fbb0f2485056ec4d2f53a5ec76dc7be9203