Remove old todo
Add support for calling type_def directly

`Algebrick.type_def self` will now work
Add #is_matching? test returning true/false
Raise when reading unknown field on a product type
Read version form a file

Add `Algebrick.version` method to return current gem version.
Raise if deprecation is not removed
Add optional field method accessors for products
white space formatting
bump v0.1.2