iOS 8: Handling of portrait and hybrid portrait/landscape
Rewrote content builder targets to support automatic building and packaging of content
avoid Sqrt , move code to ref Methods
Fix the Xamarin Studio Content Pipeline addin to build with the correct dlls

This is because the paths to the monodevleop dlls changed in the
latest release
Merge pull request #3166 from dellis1972/fixmacbuild

Fix the Xamarin Studio Content Pipeline addin to build with the correct dlls
Merge remote-tracking branch 'upstream/develop' into optimizeBoundingSphere
Merge branch 'develop' into xamarin
Merge pull request #3116 from mono/xamarin

iOS 8: Handling of portrait and hybrid portrait/landscape
Merge pull request #3163 from nkast/optimizeBoundingSphere

Optimize BoundingSphere
fix Intersects(ref BoundingBox box, out bool result)
Merge pull request #3167 from nkast/optimizeBoundingSphere

fix Intersects(ref BoundingBox box, out bool result)
Merge pull request #3138 from SongArc/feature/content_build

Rewrote content builder targets
Update README to point to new Protobuild documentation
Merge pull request #3175 from hach-que/readme-update

Update README to point to new Protobuild documentation
Correct links in project definitions for new Protobuild documentation
Merge pull request #3176 from hach-que/readme-update

Correct links in project definitions for new Protobuild documentation
Ensure pipeline builds successfully on Linux
Merge pull request #3177 from hach-que/protobuild-packages

Ensure MonoGame builds successfully on Linux