VRML-Reader: update projects, improve generation of vertex normals, fix compiler warnings.
Add clang nullability markup to pointers in public functions and structures, and fix resulting warnings.
Fix some errors when compiling for release.
Fix structure of -[Quesa3DView initwithFrame:] in Cocoa Example.
Update Cocoa Example for Xcode 10.
Changed modern Quesa project to 64-bit only.
Delete shadow VBOs with the wrong local light position. This simplifies the data structure, as we only need to store one shadow VBO for a given pair of geometry and light.
Add some warnings to Xcode configs.