Added case to typeof_global for None global value

Sometimes (for large functions), `None` uses the `LOAD_GLOBAL` instruction instead of the `LOAD_CONST` instruction, as Numba currently assumes.  This change will catch the case that `None` is loaded as a global var.
Fix discover_modules() in benchmarks/runall.py to work on Python 3.
Fix typo (s/legialize/legalize/)
Merge pull request #437 from pitrou/typo_legialize

Fix typo (s/legialize/legalize/)
s/jocabi/jacobi/
Release compile lock even when an error occurred
Use Py_XDECREF instead of Py_DECREF when the pointer could be null.
Merge pull request #438 from seibert/helper_decref

Fix segfault in _helperlib.c:Numba_recreate_record() caused by incorrect use of Py_DECREF
Fix compilation warnings
Workaround numpy issue (?) under 3.4 in Numba_recreate_record
Merge pull request #439 from pitrou/devel

Workaround numpy issue (?) under 3.4 in Numba_recreate_record
Fix spelling in error message
Enable Python 3.4 on Travis-CI builds.
Alternate approach for Numba_recreate_record that doesn't need #ifdef's
(and may also be lighter at runtime).
An even better solution: call the Numpy C API directly.
Fix build options for _helperlib to include the numpy C API
Allow compile errors to be displayed in Travis logs
Merge pull request #442 from pitrou/devel

Alternate approach for Numba_recreate_record #2
add support for NUMBAPRO_NVVM env var
Merge pull request #436 from pitrou/benchmarks-py3

Fix discover_modules() in benchmarks/runall.py to work on Python 3.