mpatch.c: Added preliminary support for py3k. This is done by including the util.h header file, that defines appropriate macros according to the current python version.

osutil.c: Support for py3k added. This patch adds support for py3k in osutil.c. This is accomplished by including a header file responsible for abstracting the API differences between python 2 and python 3. listdir_stat_type is also changed in the following way: A previous call to PyObject_HEAD_INIT is substituted to a call to PyVarObject_HEAD_INIT, which makes the object buildable in both python 2.x and 3.x without weird warnings. After testing on windows, some modifications were also made in the posixfile function, as it calls PyFile_FromFile and PyFile_SetBufSize, which are gone in py3k. In py3k the PyFile_* API is, actually a wrapper over the io module, and code has been adapted accordingly to fit py3k.

util.h: Utility macros for handling different Python APIs. If we are in py3k, a IS_PY3K symbol is defined. Apart from that, byte strings use the API defined in Python 2.6+ (_?PyBytes_.*). For Python < 2.6, the bytes API is defined accordingly for mercurial usage (shameless copy from bytesobject.h from Python's code). Some macros were backported from 2.6, as inspired by rPath's pycompat.h.

relink: ensure deterministic directory walk in collect

help: add "glossary" topic Joint work with Vishakh Harikumar, Pradeepkumar Gayam, David Champion, Mark Booth, timeless, Matt Mackall, Heinrik Stuart, Greg Ward, and Martin Geisler.

relink/progress: Adding progress for collecting stage

relink/progress: Adding progress for pruning stage