Replace deprecated library `latlong`

[danilocubos]

Updating my project's libraries, I found the following incompatibility. The problem is that latlong, which is causing the incompatibility, is deprecated. Is it possible to replace it or even implement its functions directly on flutter_map, resolving this dependencies issue? Can I help you with it?

Because no versions of flutter_map match >0.12.0 <0.13.0 and flutter_map 0.12.0 depends on latlong ^0.6.1, flutter_map ^0.12.0 requires latlong ^0.6.1.

And because no versions of latlong match >0.6.1 <0.7.0 and latlong 0.6.1 depends on logging >=0.11.3 <1.0.0, flutter_map ^0.12.0 requires logging >=0.11.3 <1.0.0.

And because moor_generator >=4.2.0 depends on build ^2.0.0 which depends on logging ^1.0.0, flutter_map ^0.12.0 is incompatible with moor_generator >=4.2.0.

So, because my_project depends on both flutter_map ^0.12.0 and moor_generator ^4.2.1, version solving failed.

[Ratatinator97]

https://pub.dev/packages/latlong2

[johnpryan]

duplicate of #485