The arguments passed to `Callback<void()>`'s constructor were the wrong way round,
thus preventing the `attach` function from being instantiated.
This patch corrects that by switching the order of the arguments.
Attach callbacks with the assignment operator rather than with the
deprecated attach function. This fixes deprecation warnings.
This patch also adds the ability to attach a Callback directly.
1. added call to busReset() to KL25Z HAL; now the USB stack survives if you disconnect the cable, similar to LPC40 2. busReset callback to update terminal_connected in USBCDC 3. new bool USBSerial::connected() to read protected terminal_connected property, useful when you want to check if the terminal is ready from main app
Pharap
Russ Butler
Anna Bridge
Christopher Haster