Patterpad 0.5.4

Fixed

• patterpad <project> --at <where> now lands correctly when Patterpad is already running. Two problems:
  on Windows the --at switch could be dropped as the launch was handed to the running window (the
  location is now forwarded over a reliable channel); and re-launching the project that was already open
  reloaded it from disk - resetting the editor to the landing scene and discarding unsaved in-memory
  state - instead of just jumping. Patterpad now jumps in place when the requested project is already
  open, and only loads when it is a different one. Cold-start --at was unaffected.