Add Timing and Sleep Functions to SmartEM and FakeDataMicroscope, and Update rescan mask method

[tathey1]

• Wrote decorator that prints how long a function takes to run, added the decorator to various smartem, microscope, and get_rescan_mask functions. It can be turned on or off by the variable time_on in timing.py
• FakeDataMicroscope can now simulate real execution by sleeping during various tasks
• Changed padding function to use cv2 which is faster
• Changed the optimization method to control a specified rescan rate
• The example script can do grid acquisition with the fakedatamicroscope