Lifetime Annotations and Inference

[thepowersgang]

Although the branch is called borrowcheck - this is just the first half of a borrow checker.

Includes:

• Storage and use of lifetime parameters through all compilation phases.
• Lifetime elision rules
• Lifetime inference - hecking of function inputs and outputs, required for closures to have lifetime annotations
• Lots of improvements to promotion of borrows of constants.

[thepowersgang]

Looks like an important patch was clobbered in the merge from master, waiting for full regression test with fixed patch.

[thepowersgang]

Full regression run passes!