CocoApi.m: updated showAnns() to use MaskApi, fixed .5 pixel shift during display
CocoApi.m: updated showAnns() to use MaskApi, fixed .5 pixel shift during display

victorgan/coco,mprat/coco,chenfsjz/coco,gnauhnoj/coco,yxliang/coco,CVML/coco,pdollar/coco,CVML/coco,pdollar/coco,yxliang/coco,gnauhnoj/coco,yxliang/coco,gnauhnoj/coco,chenfsjz/coco,victorgan/coco,CVML/coco,pdollar/coco,mprat/coco,gnauhnoj/coco,mprat/coco,yxliang/coco,pdollar/coco,victorgan/coco,mprat/coco,victorgan/coco,chenfsjz/coco,CVML/coco,chenfsjz/coco