reorganisation pass over intLang proofs
Adjust grammar and PEG for proper exception-handling syntax.

Soundness proof fixed also. Tests not yet checked because of unrelated
lexing bug.
Fix a lexer bug that was dropping characters.

Also get parsing/testing to catch the problem earlier (in its very
first test even).
Fix lexer bug that tried to lex "->bool" as one token.

Again, attempting to build parsing/testing detected the problem.
Write a basic shell-script to do some regression testing.

Edit the build-sequence file to add more directories to the test. Each
directory has Holmake cleanAll called it when visited, so the order of
the directories in the sequence should be accurate (or else you'll end
up rebuilding the same ancestral stuff multiple times).

The script will need to be run in a cron job with output sent
somewhere appropriate.
Change regression script to output current SHA, and warn if status is unclean
Merge branch 'master' into exn
Further fixes to grammar for exception handling.

Remove Exn non-terminal. Tests don't pass, and completeness doesn't
build either. Soundness is good though.