[RIF-Core] ACTION-803 - Update mathematic syntax for Core to reflect restricted lists [Done]

I completed my ACTION-803 - Update mathematic syntax for Core to reflect
restricted lists.

Updated RIF Core XML Schema
http://www.w3.org/2005/rules/wiki/Core#Condition_Language

The Terms of RIF-Core are the terms of RIF-BLD with the exclusion of
subclass terms and of terms with named arguments.
http://www.w3.org/2005/rules/wiki/Core#Terms_of_RIF-Core

EBNF Presentation Syntax of RIF Core including lists
http://www.w3.org/2005/rules/wiki/Core#EBNF_Grammar_for_the_Presentation_Syn
tax_of_RIF-Core

List terms are safe by definition, because they are alway ground in Core,
i.e. contain no variables.
http://www.w3.org/2005/rules/wiki/Core#Safeness

-Adrian