[Distutils] New customization help message for easy_install

[Phillip J. Eby]

I'm working on implementing seamless PYTHONPATH support for EasyInstall, 
and as I previously proposed, it's going to halt with an error message if 
you try to install somewhere that isn't a --site-dirs directory or on 
PYTHONPATH (and you're not doing a --multi-version install).  Since most of 
the time a "naive" user will be installing to somewhere that *is* on 
PYTHONPATH, they probably will never see this message.  But I thought it 
would be good to get some feedback on the proposed wording of the message.

-----------------------------------------------------------------------
CONFIGURATION PROBLEM

You are attempting to install a package to a directory that is not
on PYTHONPATH and is not registered as supporting Python ".pth" files.
Here are some of your options for correcting this:

* You can choose a different installation directory, i.e., one that is
   on PYTHONPATH or supports .pth files.

* You can add the installation directory to the PYTHONPATH environment
   variable.  (It must then also be on PYTHONPATH whenever you run
   Python and want to use the package(s) you are installing.)

* You can set up the installation directory to support ".pth" files,
   and configure EasyInstall to recognize this, by using one of the
   approaches described here:

   http://peak.telecommunity.com/EasyInstall.html#custom-installation-locations

Please make the appropriate changes for your system and try again.
Thank you for your patience.
-----------------------------------------------------------------------

Comments, anyone?