System

* Allow undrop (ctrl-Z) to restore a deleted block
* Add user to serial groups when installing on Linux
* Allow user to specify the port for the HTTP server
* Show project title in top bar of IDE
* For-loop can now iterate over the Unicode characters of a string or the bytes of a byte array
* Improved speed of "item of" for strings
* Make "length of" block return zero instead of giving an error for non-indexable objects (i.e. numbers and booleans)
* Make comparison operators (<, <=, >=, >) work on strings
* Faster graph drawing

Libraries:
* Added MAC address primitive to wifiPrims
* Add RC522 RFID library (thanks, José!)
* Add VL53L0X distance sensor library (thanks, José!)
* Update SGP30 CO2 sensor library (thanks, José!)
* Update Web Thing library and rename to WebThings

Translations:
* Add Greek translation (thanks, Nikos!)
* Add Português (Brasil) translation (thanks, Fernando!)

Bug fixes:
* Fix: Compiler handling of large, positive integer constants (>= 536870912)
* Fix: CLUE and CP Bluefruit hang in "broadcast" if the output buffer is full and board is not connected to IDE
* Fix: Talk bubbles and script highlights should be removed when board is disconnected
* Fix: Compacting Flash on micro:bit v2 causes serial port connection to be lost
* Fix: IDE can hang if serial port connection to is lost during script saving
* Fix: Duplicated string-only slots revert to auto when duplicated or saved in projects