Flags for transmit messages cannot be set with the Swift wrapper

[mac-can]

Stupidly, there is a copy-paste error in the CAN API Swift wrapper that prevents to set message flags other than standard frames for transmit messages.

Wrong:

    public struct Message {
        public struct Flags: OptionSet {
            // message flags as option set
            public static let StandardFrame = Flags([])
            public static let ExtendedFrame = Mode(rawValue: 0x01)
            public static let RemoteFrame = Mode(rawValue: 0x02)
            public static let CanFdLongFrame = Mode(rawValue: 0x04)
            public static let CanFdFastFrame = Mode(rawValue: 0x08)
            // message flags from C interface
            ...

Much better:

    public struct Message {
        public struct Flags: OptionSet {
            // message flags as option set
            public static let StandardFrame = Flags([])
            public static let ExtendedFrame = Flags(rawValue: 0x01)
            public static let RemoteFrame = Flags(rawValue: 0x02)
            public static let CanFdLongFrame = Flags(rawValue: 0x04)
            public static let CanFdFastFrame = Flags(rawValue: 0x08)
            // message flags from C interface
            ...

See also KvaserCAN issue #12