TODO

 - Add 'precision' method
 - Add fractional calculations
 - Add fret to fret calculations
 - Beautify POD and improve documentation
 - Add features to GUI (fretcalctk)
 - Add calc methods and tet to cgi
 - Mountain dulcimer calculations
 - Enumerate scale lengths: 'Gibson', 'Fender', etc.
 - Add just intonation calculations
