Add Circle::in_medias_res()

[thanasipantazides]

Why

If software fails mid-flight we want to recover (after catching exception) from the current state. We should start up software safely though. This means detecting current state of systems to avoid dangerous setup, like cutting bias without warning.

Things to consider

• Power state (access and parse MAX7317 output) (housekeeping commands 0x03 0x0e and 0x03 0x0f).
• Bias voltage state (for CdTe). This is tricky because there is no readable command in the DE for this. Maybe default behavior is to take data with whatever current bias is?
• Local error state.
• TCP connection state (reconnect if necessary).

[thanasipantazides]

This would help enable clean reentry into the main Circle loop if we except out of it.