[BuildTools] Stable and release scripts

[Lou Hafer]

Build-Toolies,

        I've used the prepare/commit_new_stable scripts for DyLP, Clp, Osi, and
Cbc, and I think I've shaken out the bugs for normal projects.  I can't say that
with the same certainty for ThirdParty, Data, or BuildTools itself.  I've pushed
them up to BuildTools/trunk, but watch carefully if you use them.

	*_new_stable will manufacture a Dependencies file in the course of 
execution. This is needed even if there's an existing Dependencies file because 
the script offers the option to reduce the set of externals between trunk and 
stable. It will not automatically create an XXX_VERSION symbol; the changes 
required to do that are just a bit too invasive, in my opinion. Let project 
managers edit that in on their own.

        There is a major change in architecture, which also affects
set_externals.  I've split out a file of shell functions (coin-functions) and
changed the way in which the scripts are used.  The only requirement now is that
coin-functions, set_externals, prepare_new_stable, and commit_new_stable live in
the same directory.  It's no longer necessary to copy them to the directory
where the stable candidate is under construction.  Also, commit_new_stable is
run from the same directory as prepare_new_stable, and the stable candidate is
built as a subdirectory in that directory.  prepare_new_stable executes
set_externals as part of normal operation.

        Since the whole Dependencies / set_externals thing seems to be a bit
slow to catch on, I figure the change to set_externals won't irritate too many
people.

        I'm proposing to rework prepare/commit_new_release to the same
architecture, as I get around to generating releases.  Let me know if you see
problems.

	Random question: Why is there no release for BuildTools/stable/0.6?
	
							Lou