schematics: 6502 IRQ to 6522, unused active-low inputs to VCC.
schematics: compacted PSU schematic, and clock circuit.
schematics: README updates, schematic layout tweaks.
schematics: removed 2x10 VIA header (PA + PB).
schematics: VIA exposes two 2x7 headers; port A and port B.
schematics: layout tweaks and errors corrected in schematic.
schematics: TFT+SD header, plus schematic layout changes.
schematics: renumbered parts (auto).
schematics: TFT+SD header on PORTB for shift-register.

SR used as PWM to control backlight.