FS2004 North American AT-6 Checkers Fix

FS2004 North American AT-6 Checkers Alpha Channel Fix. This fixes the alpha channel for the fuselage_t file in the file AT6_CIV2.ZIP which is a repaint of the payware AlphaSim AT-6 Texan. The at6.civ2 file is a fictitious paint scheme titled "City of Bangor Checkers".