- The LET-MATCH, IF-MATCH, MATCH-COND macros weren't exported,
and the source wasn't even loaded.
- Similarly, the entire SRE-SYNTAX-TOOLS package wasn't exported.
- The SIMPLIFY-REGEXP proc wasn't exported.
I hacked packages.scm to do the right package defining & exporting.
I also renamed let-match.scm to re-match-syntax.scm and moved the enclosing
module code from the file over to packages.scm.
-Olin