Modified boilerplate for generated ML files, which now end in .sml instead of .ml and have underscores in filenames in place of hyphens.

Minor changes: Avoid Lisp hang, ignore .svn directory for diffs

Updated to the latest version (3.4) of ACL2 and did some
reorganization and addition to support regression testing.

Pathnames only need to be edited in one place now:
.acl2holrc.bash

Edited and added README files. In particular, tests/README explains
how to run the new tests.

Deleted lisp/defaxioms.lisp.trans, an updated version of which is now
in tests/round-trip/gold/axioms.lisp (corresponding to ACL2 Version
3.4).