pathencode: convert PyString* to PyBytes*

osutil: convert PyString* to PyBytes* Continuing the conversion from PyString* to PyBytes*.

manifest: convert PyString* to PyBytes* Python 2.6 introduced PyBytesObject and PyBytes* as aliases for PyStringObject and PyString*. So on Python 2.6+, PyBytes* and PyString* are identical and this patch should be a no-op. On Python 3, PyStringObject is effectively renamed to PyUnicodeObject and PyBytesObject becomes the main type for byte strings. This patch begins the process of mass converting PyString* to PyBytes* so the C extensions use the correct type on Python 3.

merge: update doc of manifestmerge() per 18c2184c27dc p1 was renamed to wctx by 18c2184c27dc.

py3: remove superfluous indent from check-py3-compat.py

py3: make check-py3-compat.py load modules in standard manner Otherwise no code transformation would be applied to the modules which are imported only by imp.load_module(). This change means modules are imported from PYTHONPATH, not from the paths given by command arguments. This isn't always correct, but seems acceptable.

py3: include module filename in check-py3-compat.py output This change is intended to reduce noises in the next patch.

util: document we want Python type mapping to be temporary I think remapping Python C API types and functions is not a great approach. I'd prefer this whole #ifdef disappeared. Add a comment so we don't forget about it.

util: define PyInt_Type on Python 3 util.h attempts to wallpaper over C API differences between Python 2 and 3. This is not the correct approach where performance is critical. But it is good enough for the current state of the Python 3 port.

parsers: return NULL from PyInit_parsers on Python 3 This function must return a PyObject* or the compiler complains.