Ordered Initialisation of Thing Slots

[archienelson04-cpu]

Is your feature request related to a problem? Please describe.

• In a Thing's enter() method, it is not currently possible to specify that a Thing slot should be initialised before another Thing. As an example of what's currently not possible, on the OpenFlexure Microscope, the camera needs to talk to the sangaboard in enter() to set the duration of the LED's flash in synced illumination mode.

Describe the solution you'd like

• The ability to specify that a Thing should be initialised before or after another Thing.

Describe alternatives you've considered

• Delaying the function to run until after initialisation by putting a thread to sleep for 1 second.