Make field-offsets use a prefix-sum. It should be correct now.
subst-rv, subst-st, subst-bk. partial work on fresh lifetimes for block
activation.
Lifetime substitution is now noncapturing.
Currently gives up when capturing could occur instead of auto
α-converting. Breaks several tests that assumed lifetime names
are not replaced when a block is activated.
subst-ℓ should change nothing when the lifetime has no substitution.
Capture avoiding lifetime substitution for blocks.
fix incomplete pattern matching in `∨` and `∧`
use comprehension for `if-true` for single pass + being more idiomatic
Consolidate capture-avoiding substitution for blocks.
Deterministic fresh lifetime generation for block activation.
Deterministic fresh lifetime generation for function calls.
Substitute actual lifetimes for formal lifetimes in function calls.
remove `size` as duplicate of `len`; rewrite helper functions in more idiomatic Redex
Deterministic fresh lifetime generation for match.
Checking if a type is bound by a lifetime.

i.e. the lifetime of the type is not shorter than the provided
lifetime.
missing FIXMEs
removed an already resolved FIXME
Merge pull request #9 from anasazi/fix-block-fresh-lifetimes

Deterministic Fresh Lifetime Generation & Capture Avoiding Substitution
Merge pull request #7 from anasazi/fix-field-offsets

Resolve FIXME in field-offsets
Merge pull request #12 from anasazi/fixme-fixes

Add missing FIXMEs. Remove already resolved FIXME.
Merge remote-tracking branch 'philnguyen/master'

Conflicts:
	rust.rkt
Merge pull request #11 from anasazi/fix-ty-bound-by-lifetime

Implement `ty-bound-by-lifetime`
Type well-formedness.

Checking structs still needs a bit of work.