FIX: problem when compiling a literal issue! value with same name as a local word.
FIX: inverted position for used and free memory blocks in STATS/INFO.
FEAT: added SYSTEM function.

Refinements:
    /version  : returns a build string with version and timestamp of build
    /words    : returns a fresh block of global context words
    /platform : returns the platform name as a word (replaces PLATFORM? routine)

Example:

red>> system/version
== "0.3.2, 25-Mar-2013/2:03:45+1:00"
red>> system/platform
== Windows
red>> length? system/words
== 290