faster SPI and core CPU speed

CPU and SPI now use the DCO frequency (5,37MHz)
add utility to generate sine tables
new tick infrastructure
si4060: expose fsk-offset-register
sin_table: write header file
solidify faster communication with Si4060
transmit sine wave in FM FSK

this commit makes the Si4060 transmit a 1200 Hz sine wave, frequency
modulated with +-3kHz deviation. works well so far, as soon as the
si4060 started to power up in the first place. afterwards, SPI
communication is rock solid, no hangs or crashes observed. the Si4060
seems to take longer to update the offset-register every second or so,
maybe because of internal interrupts?
disable serial interrupt before APRS
increased DCO to 8MHz
correct reset behaviour for Si4060
optimisations

the sin_table was not a const[], consuming much RAM and leaving too
little stack for the program.

inlined one-time-use-functions

removed static variables where unneccesary
util: make sin_table a const
add matlab script for NCO parametering

this is a brute force script to evaulate all possible NCO parameters in
a given sample frequency range. it plots error magnitudes for baudrate,
mark and space frequency. choose X-value with small errors in all three
parameters, lookup NCO values in matrix res
major refactoring, si4060 reset more margin

main.c was cluttering up with telemetry, aprs, etc. therefore all
functions inside it that belong to a special part of the software have
been refactored inside external files.
aprs.c contains everything related to FM FSK.
hw.c contains hardware initialisation
tlm.c contains everything related to normal RTTY telemetry

also, the Si4060 reset was given even more margin, as it was causing
lock ups after some warm-up time. it really comes to light that you have
to wait for >1us, otherwise it won't respond.
nmea: get altitude in ft
implement APRS logic
fix some bugs in APRS
APRS transmission working
aprs test unit
correct WIDE path