now autocvars can have default values when the progs are compiled with fteqcc

now autocvars can have default values when the progs are compiled with fteqcc
or a similar compiler:

var float autocvar_foo = 3;
var string autocvar_whatever = "foo";

will create the cvar with value 3, or foo, if it does not exist, and otherwise
take over the value from the cvar into the global.

NOTE: THE var KEYWORD IS NECESSARY HERE! NOT USING IT MEANS THE COMPILER WILL
MERGE WITH CONSTANTS, AND YIELD VERY UNFUNNY RESULTS!

git-svn-id: svn://svn.icculus.org/twilight/trunk/darkplaces@9544 d7cf8633-e32d-0410-b094-e92efae38249