Feature Request: allow customization of GPS jamming zones and disabling of jamming

[daemotron]

Right now the jamming feature doesn't seem to make a lot of sense to me: not knowing when and where jamming occurs, it's impossible to use this feature for systematic training, while at the same time it can interfere when trying to train something else, or when flying online. Also using this feature requires a commercial grade charts subscription (unless you count try & error as a valid approach), so it definitely should be optional, and not randomly forced on pilots.