Remove highlighting for prelude types (vim)

[mahkoh]

Most of them are not even special cases in the compiler. E.g., giving Vec special highlighting makes no sense.

[mahkoh]

This looks like a reasonable subset:

" Things from the prelude (src/libstd/prelude.rs) {{{2
syn keyword rustTrait Copy Send Sized Sync
syn keyword rustTrait Add Sub Mul Div Rem Neg Not
syn keyword rustTrait BitAnd BitOr BitXor
syn keyword rustTrait Drop Deref DerefMut
syn keyword rustTrait Shl Shr Index IndexMut
syn keyword rustTrait PartialEq PartialOrd Eq Ord
syn keyword rustTrait Box

syn keyword rustSelf self
syn keyword rustBoolean true false

[mahkoh]

rust-lang/rust.vim#3