Possible hardware updates

[Peque]

• Decide between 3.3 or 5 V for MPU PCB powering
• Add an ADC reading for motor voltage
• Single user button
• Avoid using PA12 so that removing R10 from the Blue Pill is not needed
• New emitters configuration (Meiga style, with capacitors)
• Slimmer design (thinner, maybe home-made tires)
• More weight to the front
• New motors/encoders (with 2-cell battery)
• Pyboard instead of Bluepill?
• NSS fix? Adding a 10k pull-up resistor to NSS (the gyro board already has a pull-up resistor)