Convert to pinout for the Mivi POV control board.

(Doesn't seem to work yet).
Fix missing unlock in nrf GPIO config.
Fix swapped pin assignment for IRQ and CE.
Fix incorrect interrupt vectors.

The pov_sender works on the new Mivi POV control board!
Change pov_sender to receive data directly from USB.

This way no separate usb-to-serial converter is needed, and we also
avoid the bottlenecks that some of those have, preventing full 25 FPS
operation.

There is still a bug in that if the internal buffer fills up, we can
stall USB transfer and fail to re-start it again. With an 8kB buffer
and framerate_control.pl to limit the transfer to the nominam 25FPS,
this does not seem to actually happen though it would be nice to get
it fixed anyway.
Intermediate commit, working towards wireless flashing.

Refactor the pov_sender.c code to grab one packet at a time from USB;
this makes it easier to pass a debug packet over to a different
routine.

Also make corruption detection a bit more robust.
Introduce some #define's for the hardware pins and such used to communicate with the nRF24L01+

This does not fully allow to change pins arbitrarily (for example there is
unlock needed for some pin, and the IRQ handler also would need changing), but
it makes it somewhat nicer to add more code that references the SSI base
address and pins and such.
First working flash over wireless.

This version successfully can flash a test app on the target over the wireless.
(This part is the sender side, working as a USB-connected programmer on the PC).

There is still some glitches when connecting to the bootloader, if the
bootloader is not already running when wireless-flash.pl starts. This
needs to be fixed later. For now, to flash, reset the target (so it
enters the bootloader) and start the programmer while the bootloader
is still listening for packets.
Fix bug when sending initial "app reset" command to get app to enter
bootloader automatically.

It was missing the pulsing of the CE pin, causing the packet to not be sent.
Fix a timing bug when starting a Tx burst on the nRF24L01+.

The datasheet says that there must be a delay of at least 4 microseconds from
taking CE high until the next SPI activity taking CSN low.
Delete redundant #include