Remove the matlab2smt, and create appropriate other packages.

The package name matlab2smt is really ugly, and not really representative of
what it really does anymore.  Thus create an expression package for the pieces
representing an expression, and a parsers package for all parsers, including
both the variable and the Matlab parsers.  Also make
MatlabParserOperatorParseTest not rely on (now) private members.  Instead
use the toString methods to get a generator independent representation, and
test that it matches appropriately.

git-svn-id: https://groke.mcmaster.ca/svn/grad/colin/branches/TableTool_javization@10845 57e6efec-57d4-0310-aeb1-a6c144bb1a8b