Added alpha_trx433 to library
Deleted library -add to radio branch instead
Setup up barebones ChibiOS project and added details to README.md on how to compile it.

The configuration files are copied from Martlet 2 and so will likely need modification once the PCB design has been finalized.
Created 3D translational kalman filter written in C that should easily be ported over to the STM32.

I decided against using a matrix library as it seemed very wasteful given that most of the matrices were mainly 0s (the state transition matrix had 61). Instead I opted to handle the axes completely independently and write the matrix multiplications by hand.

The barometer calibration was copied from the Martlet 2 repo as I didn't see any benefit to rewriting it. The covariance update was also copied as doing it again by hand seemed like a waste of time.