After this change, a developer can now clone the project and run without the build failing due to lint errors! 😃
* I ran `swiftlint --fix` to resolve many auto-correctable issues (mostly whitespace)
* Excluded the `Meshtastic/Protobufs` directory from lint, since that code is automatically generated.
* Converted some single letter method parameters to lowercase.
* Converted several instances `force_cast` to instead use `guard` or `if let` to unwrap optional values. During this change, some of the SwiftUI views became "too complex to be solved in a reasonable time", so I broke up the views into distinct sub-expressions.
I was able to build and run the app on an iOS simulator.
It can be difficult to tell when the app is in progress of downloading map tiles
for offline use, especially when hitting a slow server like USGS or on a slow
network. Adds a download circle icon to indicate download progress to the
user. Also helpfully informs when a zoom level is outside the range.
