Support for esc in keyboard events (#274)

Author: lukeslu

Sources/Navigator/EPUB/EPUBSpreadView.swift

@@ -615,6 +615,8 @@ private extension KeyEvent {
 
             case "Backspace":
                 self.key = .backspace
+            case "Escape":
+                self.key = .escape
 
             default:
                 guard let char = dict["key"] as? String else {

Sources/Navigator/KeyEvent.swift

@@ -53,6 +53,7 @@ public enum Key: Equatable, CustomStringConvertible {
 
     // Others
     case backspace
+    case escape
 
     /// Indicates whether this key is a modifier key.
     public var isModifier: Bool {
@@ -95,6 +96,8 @@ public enum Key: Equatable, CustomStringConvertible {
                 return "Shift"
             case .backspace:
                 return "Backspace"
+            case .escape:
+                return "Escape"
         }
     }
 }
@@ -209,6 +212,8 @@ public extension Key {
             self = .option
         case .keyboardLeftShift, .keyboardRightShift:
             self = .shift
+        case .keyboardEscape:
+            self = .escape
 
         default:
             let character = key.charactersIgnoringModifiers