Declare _formatDescriptions[] in mvk_datatypes.mm as officially writable
because Clang now locates static const in non-writable memory.
Update build settings to Xcode 11.
Update MoltenVK_Runtime_UserGuide.md about embedding `libMoltenVK.dylib` in an application.
Fixes to create_dylib.sh to cleanup bitcode and architecture support.
Update to latest SPIRV-Cross version.
Update MoltenVK version to 1.0.26.
Update Xcode projects to Xcode 10.1.
Update What's New document.