Tweaked some help strings to be consistent with documentation.
Don't call 'set_final_options()' in 'run()' anymore -- that's now
guaranteed to be taken care of for us by the Distribution instance.
distributions their own directory (and .pth file).
Overhauled how we determine installation directories in
'set_final_options()' to separate platform-dependence and take
'install_path' option into account.
Added 'create_path_file()' to create path config file when 'install_path'
given.
Only run 'install_py' and 'install_ext' when, respectively, there are
some pure Python modules and some extension modules in the distribution.
'install_site_lib' and install_site_platlib' on non-POSIX platforms.
Should at least work for NT, as this is adopted from Amos Latteier's NT
patches. Also added extensive comments bitching about the inadequacy of
the current model, both under POSIX and NT (and probably other) systems.
of the 'install_py' command rather than 'build_py'. Obviously, this
meant that the 'build_py' and 'install_py' modules had to change; less
obviously, so did 'install' and 'build', since these higher-level
commands must make options available to control the lower-level
commands, and some compilation-related options had to migrate with the
code.