Replace collections that have moved out of tree
Replace collections that have moved out of tree

* TrieMap and TrieSet are gone
* TreeMap and TreeSet are replaced by BTree variants

DenisKolodin/rustc-serialize,indefini/rustc-serialize,shepmaster/rustc-serialize,rust-lang-nursery/rustc-serialize,rust-lang/rustc-serialize,rust-lang-deprecated/rustc-serialize,gbersac/rustc-serialize,ajroetker/rustc-serialize,SimonSapin/rustc-serialize