Add mechanism in Block for secondary and tertiary colours
Add mechanism in Block for secondary and tertiary colours

griffpatch/scratch-blocks,LLK/scratch-blocks,sclements/scratch-blocks,gengshenghong/scratch-blocks,LLK/scratch-blocks,gengshenghong/scratch-blocks,gengshenghong/scratch-blocks,gengshenghong/scratch-blocks,griffpatch/scratch-blocks,LLK/scratch-blocks,griffpatch/scratch-blocks,sclements/scratch-blocks,gengshenghong/scratch-blocks,griffpatch/scratch-blocks,griffpatch/scratch-blocks,sclements/scratch-blocks,LLK/scratch-blocks,sclements/scratch-blocks,LLK/scratch-blocks,sclements/scratch-blocks