use state change hook on RE rather than timer to sync GUI/RE state

[tacaswell]

See https://github.com/NSLS-II-XFP/profile_collection/blob/2c3abb38a15e043ee1f329f0176297a1f9cb3f75/startup/99-gui.py#L145

        RE.state_hook = self.handle_state_change

[tacaswell]

Done here currently:

isstools/isstools/gui.py

Lines 96 to 100 in 3277c50

	if self.RE is not None:
	self.RE.is_aborted = False
	self.timer = QtCore.QTimer()
	self.timer.timeout.connect(self.update_re_state)
	self.timer.start(1000)