swift234

Redesign how @inout propagation works in the typechecker:
 - Switch all the 'self' mutable arguments to take self as @inout, since
   binding methods to uncurried functions expose them as such.
 - Eliminate the subtype relationship between @inout and @inout(implicit),
   which means that we eliminate all sorts of weird cases where they get
   dropped (see the updated testcases).
 - Eliminate the logic in adjustLValueForReference that walks through functions
   converting @inout to @inout(implicit) in strange cases.
 - Introduce a new set of type checker constraints and conversion kinds to properly
   handle assignment operators: when rebound or curried, their input/result argument
   is exposed as @inout and requires an explicit &.  When applied directly (e.g. 
   as ++i), they get an implicit AddressOfExpr to bind the mutated lvalue as an
   @inout argument.

Overall, the short term effect of this is to fix a few old bugs handling lvalues.
The long term effect is to drive a larger wedge between implicit and explicit 
lvalues.


Swift SVN r11708