BaseParser: move all deprecated rules in their own "section" of the file
BaseParser: add all rules (except one) of RFC 5234, appendix B, section 1

The excluded rule is LWSP. The RFC does not even recommend it, so...
Optimize Javadoc imports
Use Set's .add() return code

In many places a .contains() test was done before attempting to .add(); which is
not needed.

Simplifies the code in quite a few places.