Observing scripts and commands

There is a general issue with error handling in observing scripts, in particular the way this is (not properly) handled in self made observing scripts. Extensive instructions were provided with examples on how errors can (and should be) handled when writing an observing scripts. This was added to the general guide on how to create scripts.

A command `wait-camera-state readout' exists that allows for scripting of tasks to be done in parallel (e.g., moving a filter wheel) while a detector is reading out. There is actually a danger in the use of this command in case there is no on-going exposure and the command will be waiting indefinite. A more generally applicable command `wait-camera-state not-integrating' was made that side steps this potential problem, while the documentation for the existing `wait-camera-state readout' command was updated to warn for the potential danger when using this command.

In order to increase the overall efficiency of the observing systems, a new functionality is being added to the exposure commands that makes it easier to use the readout time. Instead of waiting for the readout to finish, this time can be used for setting up a new instrument- or telescope configuration.