Make synthetic Langmuir probes and thermocouples

[eldond]

Probes measure ion saturation current, which is proportional to particle flux
Also: Te and ne

Thermocouples measure heat flux

• Define LP and thermocouple geometry in the data dictionary. A json file in OMAS dd format could be checked into the repo for this.
• Calculate all the signals (well, just sample them from the mesh, I guess, unless the probe tip spans more than one cell) and store them in the appropriate place in the dd
• Provide plot recipes for the probe and thermocouple locations
• Provide plot recipes for data vs. time

SynthDiag list on SPARC sharepoint