Add kicad project, STM32F407Zx CPU

[mck1117]

Add a kicad project, and root schematic sheet. Add a sheet for the CPU. This sheet includes basic hardware required to run the CPU (clocks, decoupling, debug, etc), and hierarchical labels to plug other stuff in to the CPU from the main sheet.

Hierarchical labels connecting the CPU to the outside world:

• SPI 1/2/3
• I2C 1/2
• USB
• CAN
• MCO 1/2 clock outputs
• 3 input capture for TIM8 (trigger input - probably could also use GPIO, but these leave open the option for using timer input capture shared with the scheduler timer, and are near the MCO pins)
• All 16 channels of ADC1/2
• The 8 channels of ADC3 that don't overlap channels of 1/2
• The 59 remaining pins as GPIO (injectors, ign, SPI chip sel, leds, magic, whatever)

Internal to the CPU's sheet:

• ARM Cortex 10-pin debug header
• USB
• HSE and LSE crystal oscillators (not complete - needs caps)
• Decoupling caps for VDD, VCAP1, VCAP2
• Reset pullup resistor + decoupling cap

Remaining CPU TODO (also enumerated on the CPU sheet):

• AVDD supply
• VREF+
• BOOT0/1

[mck1117]

And here's a PDF print from KiCad so y'all don't have to clone/open the project.

print_cpu.pdf