Resolving Duplicate Column Names

The JDBC spec says when you have duplicate columns names, the first one should be returned but this behavior isn't useful to us. What we really need is the ability to resolve those ambiguous cases in the client code.

I propose adding an additional string  to the columnNameIndexMap that would be in the format of tablename.column similar to how you would reference the columns in SQL.

I've added a test case for this use case that shows that it works and doesn't affect any existing test cases.
There should be no need for a `testrs_dup`. Just do a self-join with an alias.