Name sanitization

[flupe]

lbox does not magically sanitize name (I think it should), so we have to do it ourselves, especially when targetting Rust. But:

• lbox still applies some transformation on the names we give (enums have the first letter uppercased, for example`.
• lbox fails on same unicode symbols (e.g: Ֆ)
• Some keywords ought to be avoided entirely. (See "reserved" and "strict" keywords here: https://doc.rust-lang.org/reference/identifiers.html)