Merge translate_position and translate_client

- Expand `underlying_monitor` into `monitor_from_client` to avoid
  passing a NULL pointer to `translate_client`.
- Remove the `fit_monitor` setting (use the `--center` rule effect
  instead).
- Don't remap a window in it's last location (node invisibility would be
  the proper way to do this).
- Call `translate_client` after configure requests.
 Handle partially off-screen windows.

If a window is partially off-screen, preserve the off-screen regions.