This centralized namespace header encourages centralizing things on
umbrella headers that are a pain to maintain. Force each part of
AP_HAL_Linux to include what is used.
While at it, do some whitespace cleanups and minor changes to adhere to
coding style.
Implementation of the PX4 flow algorithm for ardupilot.
Based on the original PX4 Flow code, it has diverged a lot.
I have kept the license header since it is required.
I have removed all the unused and dead code on current implementation,
modified the code to make it clearer, re-indented it and changed
the way some params are calculated. It has been tested on PC and
on board and showed results that I assumed were OK. No optical flow
Loiter tests have been undertaken since it requires a Sonar which will
be added soon.
Limitations :
Some parts were written in ARM assembly and I rewrote them very naively
to get them to be more easily portable. A simple optimisation would be
to re-introduce assembly code for ARM as a separate asm file with
methods for fixed resolutions that would reduce a lot the amount of
calculation and memory read/writes. Then writing a version in NEON
assembly would even be more optimised and then maybe an Intel version.