added 'cropOnlyFrames' optional parameter to autocrop method
added 'cropOnlyFrames' optional parameter to autocrop method

neophob/jimp,skoa-h/jimp,oliver-moran/jimp,skoa-h/jimp,neophob/jimp,neophob/jimp,skoa-h/jimp,oliver-moran/jimp,oliver-moran/jimp