Mini Micro updated to 1.2.1

Mini Micro has been updated to version 1.2.1!  Changes include:

• new functions in the /sys/lib modules
• a new TD (tower defense) demo
• new content in /sys/pics and /sys/sounds
• mouse support in the `findFile` dialog

...and much more!  For the full announcement, see: https://dev.to/joestrout/announcing-mini-micro-121-5e3n