It used to be an MMBT2222, now it's an MMBT3904.  The new transistor is
slightly lower-spec'd, but is still more than plenty for this
application.  Also, it's a MacroFab house part, so the boards will be
even cheaper to manufacture.

Now signal vias are MacroFab's minimum size, and power vias have a
slightly smaller drill than before to not be slightly pushing
MacroFab's design rules.

Now that my pull request for the AP2204 regulators has been merged, I
can finally update the PD Buddy Sink schematic to use it.

U2 was moved to remove ambiguity.  Q1 was moved to ensure it isn't cut
off by a hole.  U1 was moved to stay away from where MacroFab put their
secret manufacturing code.

In the previous board version, there was a trace (OUT_CTRL) between the
Boot switch's pins 2 and 3.  Since those two pins are the ones that
need to be shorted to enter DFU mode, it's possible that users wanting
to upgrade the device's firmware would want to short them with a blob
of solder rather than buying a switch.  While the soldermask *should*
prevent this solder blob from shorting the OUT_CTRL line high,
soldermask can be accidentally scraped off, so I don't want to rely on
it in this case.

This commit moves the OUT_CTRL trace out from between SW1 pins 2 and 3,
and adds a keepout zone between those two pins.  This should make it
much safer to bridge those pins with a blob of solder.

Assuming I'm going to keep ordering boards from MacroFab, it makes sense
to use their house parts as much as possible.  Therefore, the next
boards will use a C&K PTS810 as the Setup switch instead of an Alps
SKQG.  In addition to saving money, this change allows room for larger
"Setup" and "GND" labels.

MacroFab wants oval drills to be marked on the board edge layer, so
that's what I'm doing.  Hopefully they'll be able to handle oval drills
better soon, given a recent comment on their blog.

My USB Type-C connectors were merged into the KiCad
Connectors_USB.pretty footprint library, so I can use it from the normal
library now.

With the VBUS symbol merged into the KiCad library, I no longer need to
use my own.  This commit changes the schematic to use the standard VBUS
symbol rather than a custom one.

The SOT-89 footprint changed its name slightly in the KiCad library,
so the voltage regulator has been updated accordingly.  It has a nice
new 3D model too.  It's not weird and blue anymore.  I like it.

The SOD-123 was also updated to have a 3D model.  The board now only
lacks models for the footprints I made myself.  Heh.

That library is getting less important though, thankfully.  Still, while
it has symbols we need, it should be accessible.

In preparation for adding a second board (the programming jig) to this
repository, I've moved the PD Buddy Sink files to their own directory.