* Referring the current haiku version explicitly is not needed, since
the RequiresUpdater takes care of setting the version of Haiku used
for building a package.
* Adjust site-packages to be writable (by moving it into non-packaged
hierarch).
* Add vendor-packages directory, where packaged python modules shall
be installed.
* Add support for automatically installing modules into vendor
directory when HAIKU_USE_VENDOR_DIRECTORIES is set.
* Drop references to 'common'-hierarchy.
Some additional patching was required to get things to build (among
other things the bz2, ssl, and related modules). Remove superfluous
Modules/timemodule.c patch.