Add proper parsing for the Matlab && operator. Required some reworking though.

Add parsing for the && operator.  However, the grammar file doesn't have an
explicit node for it.  To avoid having to create a node per such operations,
instead add a method so that they are automatically created as necessary.  Since
each one is used (repeatedly), as the level decrements stick the appropriate
operator in place.   The system will then pick up on this and handle the situation
appropriately.

git-svn-id: https://groke.mcmaster.ca/svn/grad/colin/branches/TableTool_javization@10564 57e6efec-57d4-0310-aeb1-a6c144bb1a8b