[gta02-core] PCF50633 footprint and footprints in general

[Werner Almesberger]

Dave Ball wrote:
> I've had another go,

Ah, and a few suggestions for placing measurements:

- crossed measurements like the 7.4 and 4.95 at the bottom are
  very confusing

- the same pattern with the vertical 7.4 and 4.45 is better
  because it doesn't cross but still looks a bit odd

- having two adjacent measurements face in opposite directions
  (8.6 and 8 on the left side) is a bit confusing

For the first two problems, perhaps you could put SLx and SLy
between the pads and the heat sink, and the larger measurements
all outside the package.

- Werner