ppm2tiff: support any bps value from 1 to 16
fix #55 (closed) http://bugzilla.maptools.org/show_bug.cgi?id=2505
Patch originally submited by Ludolf Holzheid ludolf.holzheid@gmx.de
fix #55 (closed) http://bugzilla.maptools.org/show_bug.cgi?id=2505
Patch originally submited by Ludolf Holzheid ludolf.holzheid@gmx.de