Methods for saving and restoring machine states during measurments/experiments

[vellosok75]

Work in progress....

Thinking how to make sure initial state of devices and pvs should be stored and then restored after a measurement finishes.

Ideas so far:

• save an initial state in a file. Delete it if measurement finishes and machine is correctly restored. If measurement stopped incorrectly, it leaves the file behind as a flag. Add methods to quickly restore the state based on that file.