[Axiom-developer] Merging build-improvements to trunk

[daly]

The change to poly.ht and poly.pht are part of a global change
I am making to fix bug #353. I'm in the process of downcasing all
filenames. This will be released as a single changeset as soon as
it is complete. It is fairly complex as downcasing #include filenames
means that all references need to be changed. So far this has 
involved 513 individual changes.

I have made a commitment to keep the git and SVN versions in sync
so I'll have to backport Gaby's change. Unfortunately this will 
collide with the #353 bug fix.

Tim