message: Use hackflight.h instead of hfcore.h
diff: #include <stdio.h>
  #include <stdint.h>
  -#include <hfcore.h>
  +#include <hackflight.h>
  #include <pids/angle.h>
  #include <pids/althold.h>
  #include <mixers/fixedpitch/quadxbf.h>
  @@ -116,8 +116,8 @@ int main(int argc, char ** argv)
  // Run core Hackflight algorithm to get motor values
  float mvals[4] = {};
  - HackflightCore::step(
  - &demands,
  + Hackflight::step(
  + demands,
  vstate,
  pidControllers, 2,
  pidReset,
  