Maintenance release
- [Bug] Apprise code crashed if no attachment was provided
- [Enhancement] Assuming that MPAD's host has provided an Apprise messaging configuration, MPAD will now send an Apprise message to its host whenever external resource files / databases are unavailable. This check currently includes: TLE and satellite frequency data, airport data and external repeater databases. The goal for this change is to provide MPAD's host with information whenever an external resource might become unavailable due to e.g. changes in the URL. This code may get extended to other online resources such as CWOP in the future.