1.1.3 - lifting and thread improvements

In this release we added new methods and fixes:

• improved threading for alvik methods accessing UART r/w
• 2 new events: on_lift and on_drop activated by the bottom proximity sensor when Alvik is lifted or dropped
• you can detected if the robot is lifted with the new method: get_lifted()
• minor REPL output improvements

Note: AlvikCarrier firmware version 1.1.1 is required to run Arduino Alvik Micropython library 1.1.3