Proper tiff support

in the previous version it was assumed that images were ARGB or RGB or RG or R but this posed quite some issues
since in scientific applications TIFF images can be found with hundreds of canals

this update assume nothing it get all it's information from the tiff headers
currently we only support GREY_SCALE and RGB (RGBA is not a tiff format, since the alpha channel is an extra channel with an alpha property)

Tiff images have a type (GREY_SCANE and RGB for example) and beyon the type you can have extra channels thoses channels are taken into account.