Add comments file for Sublime / Textmate shortcuts
Remove duplicate completions.
Add basic Yarn reference interpreter.

* Bring yarn up to date with new language features

* Remember to yarn the Prelude
Reduce root directory clutter.
Yarn is not just an interpreter.
Alias Value pointers for concision.
Factor repetition.
Make 'Choice' more type-safe.
Reduce repetition and kill dead code.
Add floating-point builtins.
Use uniform initializer instead of 'make_pair'.
Add strong user-defined type aliases.

Introduces 'type' syntax for declaring user-defined types,
as well as 'to' and 'from' syntax for constructing and
deconstructing instances thereof. UDTs may wrap any type,
including polymorphic functions, and are representationally
identical to their underlying type.

Also fixes a bug where definitions without type signatures
were assumed to be pure.

For #49
Support type definitions in REPL.

For #49
Clean up HLint test.
Lint.
Add locations to all types and report these in errors.

Closes #51
Enable optimisation and cover GHC bug.

There is a bug[1] in SpecConstr in GHC <=7.8 which causes an
infinite loop when compiling with -O2. The workaround is
simply to compile with -fno-spec-constr.

[1]: http://ghc.haskell.org/trac/ghc/ticket/5550
Move to strict data structures.

* Use strict fields.

* Prefer 'Text' to 'String' and 'Vector' to list.

* Add 'NameMap' using 'IntMap' instead of 'Map Name'.
Reinstate 'each'.
Kill 'manifestType' (it can be inferred).