Tidy up of diagrams, added circuit.

	* fritzing/minimal-shrimp.fzz: Added circuit diagram.
	* fritzing/protected-shrimp-battery.fzz: 3-battery box used.
	* fritzing/protected-shrimp-blink-battery.fzz: Likewise.
	* fritzing/protected-shrimp-pov-resistor-battery.fzz: Likewise.
	* fritzing/svg/breadboard/batterypack_3xAAA_breadboard.svg: Created.
	* fritzing/svg/schematic/embecosm_uart_schematic.svg: Created.
	* images/minimal-shrimp-circuit.png: Created.
	* images/protected-shrimp-battery.png: 3-battery box used.
	* images/protected-shrimp-blink-battery.png: Likewise.
	* images/protected-shrimp-pov-resistor-battery.png: Likewise.
	* presentations/shrimp-pov.odp: New images, added circuit diagram,
	minor layout changes.