Create more robust error trapping for MCS

The general error trapping / logging by MCS in situations where unexpected input is provided needs to be made more thorough/robust. 

This includes issues described in tickets 2307, 2299 and 2291, as well as some previous issues; 

• back illuminator off (no spots)
• fiducial fibres off
• scattered light in image due to dome lights being on
• wrong transformation / geometry file
• cobra_target table is wrong or empty
• failure of the transformation refinement

The appropriate behaviour of the actor depends on the situation and can be

• write a message to the log and proceed as normal
• raise an error at the higher level (e.g. IIC) to alert people that something is wrong
• raise an error telling the higher level to abort the sequence