This can happen in environments like plugins, where cacao can exist multiple times and thus tries to create and register its objc classes more than once.
- Changes internal target_os flags to be feature flags; macOS is now
appkit, and iOS/tvOS are now uikit. This enables platforms that are
not Apple-specific platforms that use frameworks to be compiled for.
- Updates the examples to handle closing/quitting better.
- Corrects `feature` -> `target_os` checks.
- Updates the old iOS scene delegate pieces to use the new class
structure.
- Bundles in an iOS demo app.
- Blocks off most things that should not even attempt to compile for
iOS.
- Adds support for NSSplitViewController.
- Reworks NSMenu support to be cleaner with enum variants.
- Reworks the Foundation underpinnings to be a bit safer and more clear
in how they're used and passed around.
- Changes to docs structure for push towards v0.1.
- Examples updated to account for changes.
