Changes

Some important fixes to parseImage.py headless output mode
Add experimental support for Autel and Parrot drone makes
Add a prominent user warning for possible in-accurate target results from Autel photo(s) metadata
- This is likely due to poor quality sensor data from this make, but not yet confirmed
Add support for varied XMP metadata from images of varying firmware versions for Autel and Skydio drones
Improve README.md and other documentation

Credit

Thanks to numerous contributors for their assistance in providing good test images from various drone makes and models
- LaunchedPix and somewhereinusa in the SkydioPilots forum:
- Matt from Nebraska in the AutelPilots forum
- reddit user /u/GeekOnTheWing, multiple Autel images, subreddit drones.reddit.com
- Vaakefjell from 🇳🇴, in the ParrotPilots forum for good 🦜 drone image samples, model spec. information, and drone image metadata

See you space cowboy...