Make enhancements

[BALATON Zoltan]

Hello,

I'm trying to get back to do some work on GNUstep. As a start I started to 
implement a feature in make that I was missing: the ability to build 
outside the source directory. There was already a half-working way in make 
via GNUSTEP_BUILD_DIR but it was not finished and didn't work for more 
complex projects (such as core). I took a different approach and 
intruduced GNUSTEP_SOURCE_DIR and used VPATH instead which is how e.g. 
automake does it.

During the above I've also reorganised the recently added GNUstep.conf 
stuff which broke non-flattened setups badly by causing make not finding 
the config.make file which is installed in a target specific directory but 
which also contained paths to the config file (a chicken and egg problem).

I hope Nicola (if he is still around) or someone else can review and 
approve my patch which is not complete yet but with some small patches it 
can compile base with the sources residing in a read only derectory.
The patches can be found at:
http://goliat.eik.bme.hu/~balaton/gnustep/gnustep-make.patch.gz
http://goliat.eik.bme.hu/~balaton/gnustep/gnustep-base.patch.gz

(These may not apply cleanly because I couldn't figure out how to tell svn 
to represent file copy and move operations also in the patch.
When trying 'svn status -u' I'm also getting the following errors:
svn: REPORT request failed on 'http://svn.gna.org/svn/gnustep/tools/make/trunk'
svn: The requested report is unknown.)

I hope to have some time to work on GNUstep in the future so I'd like to 
sign a copyright assignment for the next three years or so (and all past 
contributions) if it can be arranged. Adam, can you help me in this please?

Regards,
BALATON Zoltan