osgEarth 3.6 - upcoming changes - RFC

[gwaldron]

Friends,
The upcoming osgEarth version 3.6 will incorporate a couple key infrastructure changes, so please let us know if you have any feedback.

1. CMake build system refactor. We are refactoring the (very old) CMake setup to use more modern CMake techniques resulting in a much cleaner build setup. We will incorporate this change into the master branch before going up to 3.6; please test and provide feedback to help us make it a clean transition.

2. We want to bump the C++ version requirement to C++14 for version 3.6. If this is a showstopper for anyone, please chime in.

Thanks as always for your support.