Enable dragging toolbars in Eye Gaze Mode

I added this restriction originally because:

- It's in the way when it comes to dwell clicking. Highlighting the
  whole toolbar is confusing and distracting when you're just trying to
  select tools (or colors). The dwell clicker's `targets` filter
  takes care of that.
- I probably didn't want to deal with the component scaling when
  calculating the rectangles for drag previews.
- The floating buttons get cut off when the tool box is undocked,
  since it collapses the left docking area.
  (I still need to deal with this.)

...but the situation has changed:

- The monolithic "Eye Gaze Mode" feature is being broken up into more
  granular features, and for a granular feature of "dwell clicking",
  it feels weirder to restrict something like this.
- Toggling Eye Gaze Mode no longer resets the tool box position,
  since commit 796c145.
  - This let it become "stuck" in a non-uniform state.
    (I failed to fully consider resetting the docking state as a reason
    that I was destroying and recreating the components.)
  - It also let the tool box stay undocked as a tool window, but
    with this restriction, dragging the tool window by its title bar
    was blocked, despite supporting dragging other windows, and
    despite the dwell clicker visibly targeting all title bars,
    making it inconsistent.
- I've implemented handling for scaled components when previewing drags.
  (It wasn't actually that complicated, but it's easy to imagine not
  wanting to think about it.)

It feels right to remove the restriction, when using the mouse.

Author: 1j01

src/$Component.js

@@ -303,8 +303,6 @@ function $Component(title, className, orientation, $el) {
 				$(e.target).closest("button").length === 0
 			);
 		if (!validTarget) { return; }
-		// Don't allow dragging in eye gaze mode
-		if ($("body").hasClass("eye-gaze-mode")) { return; }
 
 		const docked = imagine_docked_dimensions();
 		const rect = $c[0].getBoundingClientRect();