A MIDI enabled Theremin which also is a digital synthesizer

The idea behind this ThereMIDIn project is to control synthesizers and espacially soft-synths just by moving your hands. The original Theremin is the oldest known electronic instrument its principle is simple. Two RF-antennas create two electric fields, which can be manipulated with your own electric field (or the field of whatever). In the original design, one antenna controls the pitch of the outcoming sound and the other one controls the volume.

But, how cool would it be to control ANY parameter of ANY synthesizer just by moving your hands? It would be awesome, that's right :)

Because the class 'BandPassFilter' inherits from the class 'AudioFilterStateVariable' (which is part of the Audio library), some private methods in filter_variable.h need to be declared as protected:

Change from (line 68): 'private: void update_fixed(const int16_t *in, int16_t *lp, int16_t *bp, int16_t *hp); void update_variable(const int16_t *in, const int16_t *ctl, int16_t *lp, int16_t *bp, int16_t *hp);'

To: 'protected: void update_fixed(const int16_t *in, int16_t *lp, int16_t *bp, int16_t *hp); void update_variable(const int16_t *in, const int16_t *ctl, int16_t *lp, int16_t *bp, int16_t *hp);'