Problem of override default __eq__ in Panel

[louxiu]

	def __eq__(self, other):
		return all(
			[
				abs(self.x - other.x) < self.wt(),
				abs(self.y - other.y) < self.ht(),
				abs(self.r - other.r) < self.wt(),
				abs(self.b - other.b) < self.ht(),
			]
		)

Override __eq__ of Panel cause problem. Assume panel_a is __eq__ to panel_b and panel_b is __eq__ to panel_c, but it is may not true that panel_a is __eq__ to panel_c.
If panel_a, panel_b, panel_c are in panels array(order a b c) and we remove it with.order panel_b, panel_c, panel_a, then panel_a, panel_b will be remove in order, and error will occur when try to remove pane_a because panel_c is left in panels array. This may happens in merge_panes in page.py

Maybe we should avoid override default __eq__ (lt) etc and use explicit func with similar top_left etc