System
  * Menu option to put zero at bottom or middle of graph (defaults to middle)
  * Show script size in bytes in output of "show compiled bytes"
  * Arrow key navigation in scrollable morph under mouse pointer (closes #182)

Libraries
  * RTTL Ringtone library for playing tunes
  * Microphone library
  * String library

VM
  * Added microphone primitive (not yet supported on M5Stick C)

Bug Fixes
  * Fix: Use DAC for output on analog output to A0 on CPX