Add WordComponent::appendConstantValue method
Add WordComponent::isRawString method
Remove non-const Word::components

The components vector has to be encapsulated to implement a value cache
safely in the next commit.
Add Word::maybeConstantValue method
Add Word::isRawString method
Add Keyword class
Add EnumSet class template
Fix file order in Makefile.am
Add Token class alias
Add CommentParser class
Add isBlank function
Add BlankAndCommentParser class
Fix result of contains method
Merge features required for TokenParser
Add AssignmentParserStub and WordParserStub classes
Add TokenParser abstract class
Add TokenParserImpl class
Merge pull request #47 from magicant/feature/tokenparser

Implementation of new token parser