what are the changes?

schematic redesign from schratch just for fun :)
buck convertor - now motrix can handle 6-20V without firing anything
3 ultrasonic headers - especially for robosumo freaks, shared TRIG solves pincount problem

problems i’ve faced through

pincount problem - i had 3 options:

1. sacrifice the debug LED
2. sacrifice 2nd servo
3. sacrifice 3rd ultrasonic
   o_o
   so i choose the 1st option.
   i mean, i can just make separate debug LED that works on analog, but who cares?
   looks like i care!