"Fix" getStringForKeyCode returning incorrect strings (#753)

* Fix getStringForKeyCode returning wrong result

This adds the full stop/period (.) key to the switch statement, and replaces String.fromCharCode (which works with Unicode) with the replacement character (�).

* Make letter keys work properly

* Add digits and display unknown codes in brackets

* better formatting

src/js/game/key_action_mapper.js

@@ -248,6 +248,8 @@ export function getStringForKeyCode(code) {
             return ",";
         case 189:
             return "-";
+        case 190:
+            return ".";
         case 191:
             return "/";
         case 219:
@@ -260,7 +262,9 @@ export function getStringForKeyCode(code) {
             return "'";
     }
 
-    return String.fromCharCode(code);
+    return (48 <= code && code <= 57) || (65 <= code && code <= 90)
+        ? String.fromCharCode(code)
+        : "[" + code + "]";
 }
 
 export class Keybinding {