small bug fix: in postscript, clip does not consume the current path, so
if we don't do an explicit "newpath", the next command simply adds to the
clip path. (This led to a strange "box around the clip path" when the first
primitive after a clip was a line--since for a line we did not start a
new path.) Now we just add "newpath" when we start a new line, which is
the right thing (TM) to do anyway.