Print all where statements

[tcr]

There are a few control groups (of do, let, and case) that don't handle where right.

1. They parse their body as a list of statements and then where, so where first needs to be stripped from the body.
2. The where clause should be asserted to be the last item in the body.
3. Then the where clause should have its own parameter in the AST node. Then it should be checked that all of these are printed in main.rs

[tcr]

Another example:

toRustType (IsPtr mut to) = let Rust.TypeName to' = toRustType to in Rust.TypeName (rustMut mut ++ to')
    where
    rustMut Rust.Mutable = "*mut "
    rustMut Rust.Immutable = "*const "