Add custom Don

- Registered users can customise the colour of their Don and it will appear for other players
- Bug fixes:
  - Add lyrics checkbox to admin page
  - 2P shows above "creative" or "with lyrics" labels
  - Prevent accidental alt and menu keyboard presses from triggering browser menus
  - Fixed mouse hitboxes on difficulty selection
  - Clean cached sounds and lyrics when another song is loading
  - Fixed debug jumping to the top-left of the screen when hidden
  - Fixed server volume not being applied to songs

public/src/js/strings.js

@@ -995,8 +995,23 @@ var translations = {
 			en: "Save",
 		},
 		displayName: {
+			ja: null,
 			en: "Displayed Name",
 		},
+		customdon: {
+			bodyFill: {
+				ja: null,
+				en: "Body",
+			},
+			faceFill: {
+				ja: null,
+				en: "Face",
+			},
+			reset: {
+				ja: null,
+				en: "Reset",
+			}
+		},
 		changePassword: {
 			ja: null,
 			en: "Change Password",
@@ -1043,6 +1058,10 @@ var translations = {
 			ja: null,
 			en: "Cannot use this name, please check that your new name is at most 25 characters long",
 		},
+		invalid_don: {
+			ja: null,
+			en: "Could not save your custom Don"
+		},
 		current_password_invalid: {
 			ja: null,
 			en: "Current password does not match",