Correctly parse let nodes with the right bindings form node class.
Compile as regular statements any non-first ns-expressions.
Clear RootNode's raw-ns at each repeat of the REPL.

This allows the repl's namespace to be correctly set if an ns expression is entered.
Don't add splatted parameters to the function definition's param list.
Make prn's signature vararg-friendly.
Change the repl's namespace to pharen.repl.
Escape any backslashes in the namespace name when compiling a lambda and outputting its string form.