AbstractOverlay.__init__ is redundant

[corranwebster]

enable/enable/abstract_overlay.py

Lines 61 to 64 in 84f75d3

	def __init__(self, component=None, *args, **kw):
	if component is not None:
	self.component = component
	super(AbstractOverlay, self).__init__(*args, **kw)

There seems to be no need for special-handling of the component trait - it can just be added to the keywords and passed through.