Bugfix: Triangle reader was a factor 2 off from the frequency it should have.
Refactoring: Renaming Square to Threshold.
Bugfix: Missing position initialization for SndFileWriter.
Generators: Added new generators for sawtooth and square waves.
Demo: demo to show the different signal generators.

* Sawtooth
* Silence
* Sine
* Square
* Triangle
C API: Added all wave generators to the API.