Move print directive syntax registration from the parser to the main package.

This should provide more clean and coherent interface.
Add proper handling of the parameters in the user print directives

The create rule is slightly different from the supplied:
    1. Proper handling of the "|" and white space is added around rule
    2. The code inside DEFINE-PRINT-SYNTAX is surrounded with :AROUND
       directive to properly tag the user print directive inside the
       print command.

To achieve all above, the print directive syntax is refactored to have
a rule with all directives and handle white space in the single place.
Remove WRAP-USER-PRINT-DIRECTIVE macro because it is used only in the single place
Remove list of all custom print directives

After adding checks that custom print directive doesn't have symbol
equal to standard directive or Esrap operation, separate list of the
directives is redundant and removed.
Move Common Lisp print directive handler list out of parser
Clean up Javascript and RequireJS support
Add documentation to the DEFINE-PRINT-SYNTAX
Make return value of the REGISTER-PRINT-HANDLER the same across backends

The function noew returns the symbol which identify print directive.