lcs-electronics-intro: rendering fixes

- Redo schematic layout for all Fritzing diagrams; Fritzing appears to
  have forgotten all the previous layout I did!
- Re-export all Fritzing schematics to SVG and reimport those into the
  presentation. This mostly solves this missing rendering of LEDs in OOo.
  However, the light arrows from the LEDs still don't render with arrows.
- Fix inconsistent shade of yellow used in presentation popouts.