Shortened feat description

concept of using a new PRERULE (as per spells description) to allow for
more concise feat descriptions by default.

Would require the following to be added to the
'system\gameModes\35e\rules.lst'
NAME:UseFullFeatDescriptions  VAR:DisplayFullFeat DEFAULT:No
DESC:Use Full Feat Descriptions from the Core Books (adds text that may
be superflous)
Source/Page for vision modes

Refer to the PHB source rather than UR for vision modes.