v2.0.0-alpha.42

Optimize access to Task.current and calls to identical.
Fix a few issues with the BLE stack.
Add AES functions for GCM mode, used by TLS.
Remove check whether port is character device in tools/firmware on windows.
Disable DTLS supporton ESP32 targets.
Add cursor to buffered readers .
Allow an odd number of hex digits in encoding.hex.decode.
Fix flashing on Windows.
Rewrite 'pin.wait_for'.