Add GamePrefix setting to allow multiple games.

It can be an absolute or relative directory, a filename prefix, or both.
ie: "/sbbs/xtrn/lord/netlord/" will be in the netlord directory.
    "/sbbs/xtrn/lord/netlord"  will prefix all the files with "netlord"
                               unless a netlord directory exists.
    "netlord/"                 same as #1, relative to exec dir.
    "netlord"                  same as #2, relative to exec dir.

xtrn/lord/lord.ini

@@ -20,6 +20,7 @@ BonusDefForPlayerKill=	false
 BonusStrForPlayerKill=	false
 BrokenInnWeaponSwap=	false
 ;GameServer=		portable.57038
+GamePrefix=
 
 [Tournament]
 Enabled=		false