Simplify lexer tests by introducing new checkContainsTokens function
Merge pull request #27 from jspam/013-lexer-test-assert-function

Simplify lexer tests by introducing new checkContainsTokens function
Fix typo

Actually, it's a regex substitution mistake, but who's counting.
Add literal parameter to TokenData, specifying it for each case class
Give TokenData an appropriate toString method