Simplify Hotkey parsing.

OpenRA.FileFormats/Exts.cs

@@ -262,5 +262,22 @@ namespace OpenRA
 	{
 		public static T Parse(string s) { return (T)Enum.Parse(typeof(T), s); }
 		public static T[] GetValues() { return (T[])Enum.GetValues(typeof(T)); }
+
+		public static bool TryParse(string s, bool ignoreCase, out T value)
+		{
+			// The string may be a comma delimited list of values
+			var names = ignoreCase ? Enum.GetNames(typeof(T)).Select(x => x.ToLowerInvariant()) : Enum.GetNames(typeof(T));
+			var values = ignoreCase ? s.Split(',').Select(x => x.Trim().ToLowerInvariant()) : s.Split(',').Select(x => x.Trim());
+
+			if (values.Any(x => !names.Contains(x)))
+			{
+				value = default(T);
+				return false;
+			}
+
+			value = (T)Enum.Parse(typeof(T), s, ignoreCase);
+
+			return true;
+		}
 	}
 }