change interface to add_persistent_funs (#73) and fix more calls

The new interface takes a list of strings naming theorems.
(The old interface took a list of (string * thm) pairs.)
The new way better ensures consistency of theory development and theory
load behaviour: you can no longer pass a name with a theorem that isn't
actually saved under it.

Theorems are looked up with DB.theorem, or failing that, DB.definition
or DB.axiom.

Alas, I found more examples using add_persistent_funs to add theorems in
ancestor theories. Rather than modify the ancestor theories, I have
opted to make the offending theories save the theorems they want to add
to computeLib themselves so they have a name in the current theory to
pass to add_persistent_funs.

If this behavior was appropriate for patricia too (da47401) change it.
Alternatively, if the ancestor theories should have exported those
things for computeLib anyway, search this commit for new instances of
"save_thm" to see what needs fixing.

Removed trailing whitespace from all .sml and .sig files.

This affects over 900 files and was done using emacs's delete-trailing-whitespace
function in batch mode. Building the system with Poly/ML and Moscow ML seems to
work, so I'm hoping these changes don't break anything. Please complain if
they do!

Finally add same directory with different name.