Fixes#543
```ql
newtype TA = TB()
private predicate foo() { any() }
```
Our TextMate grammar didn't realize that the newtype declaration ended after the closing paren of the branch's parameter list, so the `private` modifier was highlighted incorrectly.
It's surprisingly tricky to get TextMate to handle this correctly, so I wound up just treating the IPA declaration head (`newtype TA`), the branch head (`= TB`), the branch parameter list, and the branch body as directly children of the module body. This is kind of hacky, but it does fix the bug without introducing any new cases where we have incorrect highlighting of valid code.
`unique` is really a context-sensitive keyword, but that's even more of a hassle in a TextMate grammars than it is in the compiler itself. We'll just highlight it as a real keyword. The worst that will happen is that existing variables and predicates named "unique" will be highlighted like keywords, which will hopefully just encourage QL developers to rename those anyway.
