Move AIN1 track to top layer

Move the AIN1 track to the top layer, and the move the adjacent GND track to the
bottom layer.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Optimize power delivery and reduce number of vias

Route the GND through the bottom layer, and the +5V and -5V power rails through
the top rail. The number of vias is reduced from 44 to 35 (-9).

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Fix entry angle for ground pads on filled zones

On zones filled with copper (in our case, ground planes), tracks must come in
through the path that the zone will connect to the pad. this means a 45 degree
approach angle for round pads, and a vertical or horizontal approach for
rectangular pads.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Add pull-up resistor for the soft-start circuit

The microcontroller can never bring the voltage on the gate of the soft-start
MOSFET to the 5V needed to turn off power. To only way to achieve 5V is to have
a pull-up resistor, and let the control pin in high-impedance mode.
When the control pin is configured as an output, and (preferrably) set low, the
osciboost module will be powered on. To power off the module, the pin is put
into high-impedance mode.

Add a 10k pull-up resistor to enable the power-off circuit to function
correctly.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>