Bug fixes to DexLint

Corrected path to picture files to always use path specified by command
line argument pictures=.
Corrected bug wherein message/pictures for the visibility checks were
omitted from the proofs (but not from the automatically generated list
of pictures). Added code to detect if other commands that use pictures
are not handled by the proofs generator.
Temporarily supress circle in COP display.
Hold a minor correction for later use.