Update help content and refactor new routine in php_help.c

*  I've added more content to the help to expand desciption for new-to-phpdbg
   developers.

*  After a code review of the new routines that I've added to the help module,
   I've decided that the implementation was unnecessarily convolved and that
   Keep-It-Simple-Stupid would be more understandable, maintainable and have
   no material performance hit.