Change mutability combinators to only add annotations (not remove any)
Added some comments to basic annotation functions
First draft of remove-bind transformation
Fixed up RemoveRoBind tranformation
Made syntax missing annotation errors even clearer
ro_bindings: Always use letIns and fresh variable names

It gets too messy trying to use built-in variables because of variable
capture. Now we always rename to fresh variable names to make sure we
can always project correctly.
Remove warnings from a bunch of files