Path/environment variable changes.

[Richard Frith-Macdonald]

After much messing around, I think there is now something like stable 
code in place
for handling the locations in which user defaults and user files are to 
be found.

This is new stuff though ... so it's very likely I've missed updating 
something and
need to fix a few bugs.

The make package now builds a little C tool (called user_home) which can 
be used to
return the location of the current users
 unix/windoze home directory, gnustep defaults root, or gnustep user root

This tool is used as the definitive source for this information by the 
GNUstep.sh
script.  The GNUSTEP_USER_ROOT and GNUSTEP_DEFAULTS_ROOT environment 
variables are
set up from the values returned by the tool ... and they are no longer 
used in any
way by any GNUstep program, they are merely provided for use by the make 
package
and shell scripts.  This means that you should not modify these 
variables.

If you use the --with-user-root or --with-defaults-root options when 
configuring
the makefiles package, the utility hard-codes the appropriate roots, so 
the same
roots are used by *all* users of the system.

If you haven't forced hard coded roots to be used, when a user wishes to 
change
their roots, they can edit a .GNUsteprc file in their home directory.
The user_home tool will read this file for lines of the format
GNUSTEP_DEFAULTS_ROOT=path
or
GNUSTEP_USER_ROOT=path
and return the results instead of the default location (which is the 
GNUstep
subdirectory of the unix/windoze home directory).

I hope all that makes sense.  For most people who simply accept a 
default setup,
everything should continue to behave as before.

For setuid applications which change the user they are running as,
the new scheme should ensure that when running as a new user the
correct defaults and file locations are reliably located.