v2.0.0-alpha.161

Add more commands to the 'toit' executable.
Sign macOS release and include ARM executables for macOS.
Enable asserts by default for -O0 and -O1 and add flag.
Infer literal types.
Warn when conditions are always true due to nullables.
Check type when assigning to typed globals.
Add cryptographic random.
Use '--initial' for List and ByteArray constructors.
Move UUID functions into class.
Add support for generating random UUIDs.
Add static typing for data-bytes of UUIDs.
Add Duration.parse.
Expose True and False and use it for flags that must be true.
Add work-around for spurious first byte on the UART.
Use correct network for DNS requests.
Make wifi state management more robust.
Improve and expose SPI devices for Linux.
Don't timeout early if there is a sleep.
Fix esptool lookup for 'toit tool firmware'.
Fix I2C timeout.
Fix RMT regression.
Fix BLE on macOS.
Fix UART flush.