Add more info to python README and revert package name change
Change the python bindings package name back to 'openbabel', but make clear in the Python README that this is just the python bindings, not the main Open Babel library, just in case anyone stumbles across the PyPI page by accident.
Make pkg-config check more robust and allow manual override
Add a sensible fallback if pkg-config fails to locate the Open Babel include and library directories, and a helpful error message if that fallback also fails.
Allow Open Babel include and library directories to be manually specified as command line options to setup.py using the build_ext command with -I and -L options.
The setup.py build and install commands run a number of subcommands, including build_ext, which runs SWIG to generate openbabel.py, and build_py, which copies openbabel.py and other python sources to the build directory.
The default ordering is for build_py to be run before build_ext, causing errors as build_py attempts to copy openbabel.py before it exists. This change ensures build_ext is always run first at the start of both the build and install commands.
