The current implementation removes parameters if they are used - however, it only removes the first instance, and removes instances by index. However, when multiple items are being removed, following indices must be decremented by 1 to account for previously removed items.
Make a few changes in the toplevel src dir to help separate
templates from code. Specifically, we rename `src/mako` to
`src/generator`, and nest the mako templates inside a
`src/generator/templates` dir.
This isolates most Python code into the `src/generator/lib` dir.
