Also don't advance to next file after running a command on the current
file, in the case where the current file didn't exist in its current
location when qiv-command was initiated - potentially allowing
qiv-command to perhaps perform an "undo" on that file, and not result
in automatically advancing to the next file, even when rereading that
file still causes an error.
There are times when you want qiv-command to be able to move a file to
another location and no longer be in the active list of files being
displayed by qiv, but you also want to be able to go back to that file
(a bit like delete/undelete). So qiv's default behaviour of
completely removing the file that fails to load from the list of
images is not quite what you want. Instead, --no_error_purge simply
advances to the next image in response to qiv-command returning and
the file no longer existing, or displays the error page (blank blue
screen) when failing to load the image from scratch.