Add license
Add stubs and tests for rest of rules to pass compiler. NOTE: It is not runnable
Implement `OpTree` nodes. Compilable but still tests are failed
Implement `zeroOrMore`
Implement `optional`
Implement `oneOrMore`
Fix `optional` to be algebraic
Simplify sugared expressions
Implement `not-predicate` (`!`)
Implement `and-predicate` (`&`)
`Optional` should not be inherited from `FirstOf`. As well as `AndPredicate` to `NotPredicate`
Upgrade to SBT 0.12.4
Add shapeless dependency
Rename `||`, `charRule` and `stringRule` to their parboiled 1.x counterparts
Improve AST-matching DRYness and performance, improve AndPredicate and Optional rendering
Reorganize tests
Reduce `case class test(...` to `def testRule` of reusable `TestParser`
Implement same technique for `ComplexParserSpec`
Implement `SimpleCalculator` instead of `ComplexParser`

Fix `zeroOrMore` bug
Move `Match` and `Mismatch` to trait