Operators seem to have an `assignment` keyword
Add g:swift_no_fold setting to optionally disable folding
Highlight a bunch of the built-in types
Fix subscripts

Support get/set, access control, and modifiers in subscripts, just like
in var.

Fix a couple of issues with var:
* Newlines weren't supported after the `var` keyword
* Providing an argument to `set` didn't properly close the group.
Be more conservative with function matching

Not all `func` keywords end up having a braced body. Notably, @asmname()
can let you declare a function without implementing it, and coloring the
output of Swift module documentation elides function bodies.
Support the unowned declaration modifier
Support `keyword` identifiers
Handle generics on definitions

The more conservative function definition didn't handle generics
properly. Teach it, and type definitions, how to actually identify the
generic parameter list.
Support class/static declaration modifiers
Be more conservative about var definitions

Define a region that matches a single type (hopefully), so we can
prevent var definitions from leaking past their end.
Add more standard library types/protocols

Tweak highlighting of protocols to be different than types.