Removed debugging stuff from usart_dma_test
Moving Contiki filesystems docs to a better location in the module tree.

This hierarchy was from the Contiki documentation.
We now use M_PI everywhere.
Update position module description in docs.
Fleshing out docs and some minor refactoring in timing.
Coding style fixes for files under board/
Coding style fixes for files under peripherals/
Change binary output name.
Documentation tweaks.
Stylistic updates to files in board/nap/
Rename conf -> nap_conf. Makes it clear its the SwiftNAP configuration.
Minor docs tweak (NAP -> SwiftNAP)
Documenting local coffee filesystem configuration.
Get rid of old screaming_death, rename speaking->screaming.
Tidy up init a bit.
More tidying, settings and NMEA.
More coding style updates.
Merge remote-tracking branch 'remotes/fergus/master'
Tidy main a little and re-enable NMEA.
More descriptive error message.