Cleaned up code
Windows are now selected via EnterNotify events
Improved response time on rectangle drawing (no longer creates new rectangles when window selection changes, waits 0.01 seconds between re-drawing for xorg to catch up and display)
Removed offset settings as they seem useless
Added --version option
--nodecorations now doesn't attempt to actively search for the correct subwindow. Now it just allows for selection of subwindows. This should keep slop from crashing/not work properly on weird WMs like openbox, but may make it act a little unexpectedly since you can still click on decorations to include them.
Added error handler that catches the non-fatal BadAccess error, added a DestroyNotify blocker that waits for the window to be destroyed before actually shutting down, and now we're using SFML's way of detecting keyboard presses.