Migrated to ARC, removing any remaining MRC compatibility code.
Cleaned up/fixed property declarations.
Removed obsolete c++ "extern C" guard.
Modernised enum declarations by migrating to NS_ENUM.
Refactored DLCLConstraint to now be a thin wrapper around the just introduced DLCLConstraintStruct. Faster and reduces code redundancy with DLCLConstraintLayoutPlusPlus companion project.
Fixed header import and removed commented line in sample view controller.