message: Library:; clarify ifndef/define for AudioEffectGain_F32
diff: * MIT License. use at your own risk.
  */
  -#ifndef _AudioEffectGain_h
  -#define _AudioEffectGain_h
  +#ifndef _AudioEffectGain_F32_h
  +#define _AudioEffectGain_F32_h
  #include <arm_math.h> //ARM DSP extensions. for speed!
  #include <AudioStream_F32.h>
  