Doc: fixing miscellaneous warnings and missing refs
move PyPy porting doc page to userguide (not a tutorial), move early-binding page more to the front

--HG--
rename : docs/src/tutorial/pypy.rst => docs/src/userguide/pypy.rst
rst fix
merge

--HG--
rename : docs/src/tutorial/pypy.rst => docs/src/userguide/pypy.rst
support 'from __future__ import absolute_import'
minor code simplification
disable gdb support for --debug convenience option in Py<=2.5
comment
properly cast char* argument for PyBytes_FromString() from other char* types
clean up code generation in CmpNode and fix bug #784: conflicting result types for cascaded comparisons
fix try-finally usage in STL vector test
added 'except +' and 'nogil' declarations to shipped STL constructors
added C++ vector test that operates in nogil mode
added new failing C++ test for iterating over the pointer to a C++ vector
added new failing C++ test for using a stack allocate C++ vector inside of a generator
Fix cpp iterator test.
Fix template types as class members.
Another cpp-class-as-cdef-class-member fix, fix test with side effect.
Fix C++ template subclassing.
Fix template comparison.