Add OakTheme: An Objective-C version of theme_t

This doesn’t do any caching of style lookups so performance is worse than theme_t and it also lacks an API to control the initial base font.

For now, the intention is to use this for system dialogs, such as the Find dialog, but long-term it should also be used by OakTextView, at which point, caching and base font support should be added.

Frameworks/theme/src/OakTheme.h

@@ -0,0 +1,27 @@
+#include <bundles/bundles.h>
+#include <scope/scope.h>
+
+@class OakThemeStyles;
+
+@interface OakTheme : NSObject
+@property (nonatomic, readonly) NSUUID* identifier;
+@property (nonatomic, readonly) NSColor* foregroundColor;
+@property (nonatomic, readonly) NSColor* backgroundColor;
+@property (nonatomic, readonly) NSFont* font;
++ (instancetype)theme;
+- (instancetype)initWithBundleItem:(bundles::item_ptr const&)themeItem;
+- (OakThemeStyles*)stylesForScope:(scope::scope_t const&)scope;
+@end
+
+@interface OakThemeStyles : NSObject
+@property (nonatomic, readonly) NSColor* foregroundColor;
+@property (nonatomic, readonly) NSColor* backgroundColor;
+@property (nonatomic, readonly) NSColor* caretColor;
+@property (nonatomic, readonly) NSColor* selectionColor;
+@property (nonatomic, readonly) NSColor* invisiblesColor;
+@property (nonatomic, readonly) NSFont* font;
+@property (nonatomic, readonly) NSFontDescriptorSymbolicTraits fontTraits;
+@property (nonatomic, readonly) BOOL underlined;
+@property (nonatomic, readonly) BOOL strikethrough;
+@property (nonatomic, readonly) BOOL misspelled;
+@end