Minor overhauling.

browse: take advantage of new dwm-athens control stuff (dwm -x):
  -w            opens always a new firefox window.
  -a <pattern>  try to find an existing instance which title matches the pattern.
  Default:      try to find a visible (i.e. in current tagset) firefox instance.

launchers, viewmd, etc. adapted to new browse interface.

bash refactoring: new convention: if <cond>; then, while <cond>; do, etc.