The main reason to remove the ground pads is assembly reliability. In
previous boards it was observed that it is fairly easy to create shorts
between the ground pads and signal pads of the package.

The previous footprint was causing the solder stop webbing to be very
thin which can result in the webbing missing on PCBs and result in
shorts during reflow.

The datasheet has a finer footprint with smaller pads and smaller Via
drills.

This change seems like a big diff but it only really changes SOIC-8 and
MSOP-8. They mostly bring roundrect changes and increase pad length for
better fileting.

* The 8x resistor arrays are not as common as 4x. Thus the 8x end up being
more expensive and harder to source.
* The SOT-563 package has slightly harder to solder than the SOT-363.
Also the level shifter in SOT-363 is lower cost.

All footprints that are still not roundrect in the official KiCad
library moved to local Glasgow footprint library and updated to
roundrect pads.

Also made a version of the 2x22 pin 1.27mm pitch LVDS connector with
alignment pins. This will allow us to have accurate enough position of
the connector so we can reliably connect to it in the pogopin tester and
to possible daugter boards.

As part of rerouting also moved half of the power via under the
packages. We regained some space thanks to that resulting in slightly
cleaner routing.

All part IDs and values are now meant to be printed on the Fab layer as
hardcopy manual assembly and population guide. The space on the
silkscreen used for part IDs was partly traded against logical circuit
block documentation. This is just the first pass and meant as a stepping
stone. The goal is to have the logical functionality be as self
descriptive on the silkscreen as possible.

Mainly improved readability of the Pull-Up/-Down control block legend.
This resulted in some of the passives being moved out of the way to make
space for the legend. Also added legend that indicates which level
shifter is responsible for which IO signal, including Sync.

They were not aligned in a vertical line. For aethetic reasons this is
now fixed. :)

The GPIO extenders can set a Pull-Up/-Down resistor or do nothing. That
is not the same thing as HiZ. HiZ is only true if the level shifters are
also set to input. So P- (Pull nothing or Passive) is a better term.

This is the inital routing pass. This is the status after esden's Twitch
stream on Tuesday May 26th 2020.

Replaced nono_hana with an outlive version and made the Serial Number
box an outline. This will make the black silkscreen on white solder mask
look "right". Should still work for light silk on dark solder stop.

It was decided to be DNP for poduction, but there are still regularly questions
about it popping up. So better completely remove it.

schematics part of #165 done

Also add new footprints where necessary, fix a silkscreen bug
Layout for new components still TODO

Add manufacturer names & MPNs, remove stray wire, uppercase R in resistor values

…rsion.

After testing and playing around with the small SMD tact switch we came
to the conclusion that a slightly bigger button will fit in the same
space and will give us more options. Also the longer, bigger and lower
weight tact switch will feel nicer and fit in the case better.

Also fixed up the silkscreen and fab layers.

…ane below voltage regulators

The reset button had to be TH. Logos should be virtual.

The footprint in the KiCad library works but it is too large and could
cause assembly reliability issues. The new footprint and 3D model are
based on the official Diodes Inc data and match the part we are using.

The outer pads of the resistor pack footprints were slightly too small.
This can cause assembly reliability isues.

As recommended by KiCad this setting should only be used when explicitly
asked by the PCB manufacturer. It depends on their needs and
capabilities and is usually done as part of gerber file pre processing
done by the PCB manufacturer.

Thanks @gregdavill for spotting & reporting this.