Flex temp ranges

[ctgreybeard]

I built the Thermal Camera and want to present this enhancement. It starts with the suggested temperature range but then applies a moving average to the high and low range points to adjust to what the camera is seeing. It also displays the high and low on the screen so the user can better interpret the display. I've found this useful already finding hot and cool spots on my 3D printer bed.

[caternuson]

Sorry for missing this PR. If you're still interested in submitting this, please submit as a new separate example. Can call it thermal_cam_auto_scale.ino or similar.