planned_features is a view of where the keybrd project is headed.

Top priority
============
MCP23S18 I/O expander with Serial Peripheral Interface (SPI)

Med priority
============
Add matrix-to-layout mapping array (to decouple matrix from layout)

Low priority
============
Update tutorials:
* Currently tutorial sketches are obsolete and won't compile
* Change tutorial sketches from teensy 2.0 and PCA9655E-D IOE to Teensy LC and MCP23018 IOE

Add more tutorials:
* tutorial_5_LEDs.md
* tutorial_6_mapping_matrix_to_layout.md
* tutorial_9_active_high.md
* add schematics to tutorials