Adds Mac Preferences

This makes use of `@AppStorage` for preferences. Severeral more need to migrated from AppDefaults etc.

Multiplatform/macOS/Preferences/Model/MacPreferences.swift

@@ -0,0 +1,96 @@
+//
+//  MacPreferences.swift
+//  macOS
+//
+//  Created by Stuart Breckenridge on 27/6/20.
+//
+
+import SwiftUI
+
+enum FontSize: Int {
+	case small = 0
+	case medium = 1
+	case large = 2
+	case veryLarge = 3
+}
+
+/// The `MacPreferences` object stores all macOS specific user preferences.
+class MacPreferences: ObservableObject {
+        
+    private struct AppKeys {
+        static let refreshInterval = "refreshInterval"
+        static let openInBackground = "openInBrowserInBackground"
+        static let showUnreadCountInDock = "showUnreadCountInDock"
+        static let checkForUpdatesAutomatically = "checkForAppUpdates"
+        static let downloadTestBuilds = "downloadTestBuilds"
+        static let sendCrashLogs = "sendCrashLogs"
+    }
+    
+    // Refresh Interval
+    public let refreshIntervals:[String] = RefreshFrequencies.allCases.map({ $0.description })
+    @AppStorage(wrappedValue: 0, AppKeys.refreshInterval) var refreshFrequency {
+        didSet {
+            objectWillChange.send()
+        }
+    }
+    
+    // Open in background
+    @AppStorage(wrappedValue: false, AppKeys.openInBackground) var openInBackground {
+        didSet {
+            objectWillChange.send()
+        }
+    }
+    
+    // Unread Count in Dock
+    @AppStorage(wrappedValue: true, AppKeys.showUnreadCountInDock) var showUnreadCountInDock {
+        didSet {
+            objectWillChange.send()
+        }
+    }
+    
+    // Check for App Updates
+    @AppStorage(wrappedValue: true, AppKeys.checkForUpdatesAutomatically) var checkForUpdatesAutomatically {
+        didSet {
+            objectWillChange.send()
+        }
+    }
+
+    // Test builds
+    @AppStorage(wrappedValue: false, AppKeys.downloadTestBuilds) var downloadTestBuilds {
+        didSet {
+            objectWillChange.send()
+        }
+    }
+    
+    // Crash Logs
+    @AppStorage(wrappedValue: false, AppKeys.sendCrashLogs) var sendCrashLogs {
+        didSet {
+            objectWillChange.send()
+        }
+    }
+}
+
+
+enum RefreshFrequencies: CaseIterable, CustomStringConvertible {
+    
+    case refreshEvery10Mins, refreshEvery20Mins, refreshHourly, refreshEvery2Hours, refreshEvery4Hours, refreshEvery8Hours, none
+    
+    var description: String {
+        switch self {
+        case .refreshEvery10Mins:
+            return "Every 10 minutes"
+        case .refreshEvery20Mins:
+            return "Every 20 minutes"
+        case .refreshHourly:
+            return "Every hour"
+        case .refreshEvery2Hours:
+            return "Every 2 hours"
+        case .refreshEvery4Hours:
+            return "Every 4 hours"
+        case .refreshEvery8Hours:
+            return "Every 8 hours"
+        case .none:
+            return "Manually"
+        }
+    }
+}