python/DSP/waves.py: sawtooth now has the correct amplitude range, and all formulas now use frequency as input (some used period)
python/DSP/mathutils: added arcsin and floor functions
python/DSP: pi value now inside mathutils.py
python/dsp/ changed name from waves.py to wave_functions.py
python/dsp: divided waves.py into modules: wave_functions, wave_builders, and plot_here