Add Repeat class template
Rename StringParser class

The StringParser is going to be replaced by a new implementation. The
old implementation is temporarily kept in a different name.
Add new StringParser class
Rename RawStringParser class

The RawStringParser class is going to be replaced by a new
implementation. The old implementation is temporarily kept in a
different name.
Add new RawStringParser class

The most of RawStringParser test cases are removed since they were just
duplicates of the StringParser test cases.