How to use the new SymbolTable
------------------------------
As far as your Assignment #3 code goes, nothing changes.  All of the methods
that were in the original version of SymbolTable are still there, and they
still mean the same thing.

For Assignment #4, there's only one change that you'll need to make.  In
the call() method in your SubprogramDeclaration class (or your equivalent),
you'll need to call enterSubprogramCall() at the beginning of the method
and exitSubprogramCall() at the end, rather than calling enterScope() and
exitScope().  Everything else will remain as-is.

If you made changes to the previous version of SymbolTable to make it work,
unfortunately you'll need to make them again (or figure out what I've changed
and merge those changes in, whichever is easier).

After plugging in this fix, static scoping will be used to resolve
non-local variable references, as described in the Monkie2004 specifications.

Enjoy!

- Alex
