modified `flipImageIfAxesReversed` to flip both `colorData` and `alphaData`
modified `flipImageIfAxesReversed` to flip both `colorData` and `alphaData`

LJeub/matlab2tikz,matlab2tikz/matlab2tikz,matlab2tikz/matlab2tikz,PeterPablo/matlab2tikz,egeerardyn/matlab2tikz,miscco/matlab2tikz,egeerardyn/matlab2tikz,RPeschke/matlab2tikz,nidrosianDeath/matlab2tikz