Implements another TODO.
There was a TODO about a new counter per scope, but that makes no sense. The renamer only acts on global variables, global function and parameter names, state names, and event parameters. We're already restarting the counters at every function, which is the closest to what that TODO was about.
This has been a TODO item for long. Now that we have lsllastpass, it's actually easy to implement.
Adds an LSLTypeDefaults dictionary to lslcommon, just in case the state-changing function returns a value and we need to insert a return statement.
We've also added subtree-local info to lsllastpass (lost when we return to the parent after visiting a subtree).
This fixes a bug where naked switch statements could appear as a result of optimization, and cause the compilation to fail.
lslcleanup: Variables renamed, order changed, comments added.
Other changes: remove semicolon at end of sentence, use self.Cast instead of creating a CAST node on the fly.
