new toolbar icons are problematic

[Dave Love]

The new toolbar icons appear to use up least an 8-bit colour map -- I
don't know whether they all use the same palette or whether they use
different 8-bit spaces individually and thus will exceed an 8-bit
space between them.  This clobbers 8-bit display.  For the original
icons we carefully re-mapped them to use only a few (~10?) colours
between them, and I think that needs to be done again.

Also the PBM versions are now partly (mostly?) unrecognizable, whether
as a function of starting from colour ones with certain properties, or
of how the conversion was done.  I don't remember how we did the
original PBMs -- it may have been with Gimp rather than ImageMagick's
`convert', and may have involved some hand-tuning.

Are the new ones by tigert, thus covered by the assignment for the
originals?  That's not recorded in the changelog.