RegexMatcher and PatternMatcher

abstract several methods from StringMatcher to RegexMatcher to create
base class, make StringMatcher inherit from RegexMatcher
New PatternMatcher class which is also inherit from RegexMatcher, but
save pattern to apply on differnt strings
refs #8
Bug fix and comments to RegexMatcher

no modifier append in delimit method
add some comments
toString() method return saved string or pattern.
refs #8