Fix overwrite problem in imag2d/imag2d_update
Fix ps to/from conversion to at least preserve image dimensions (and use pnmtops instead of gs).
Merge branch 'master' of ssh://pdl.git.sourceforge.net/gitroot/pdl/pdl
got a couple of commits behind...  (update pic converters so wpic/rpic
at least preserves image dimensions for ps images)