Improved apis, documentation, and examples

Minor breaking changes

• You no longer have to specify hanned_fft as part of the path to use HannedFftDetector. Example: use pitch_detector::pitch::HannedFftDetector
• detect_pitch_in_range api no longer takes an optional range.
• detect_note_in_range api also no longer takes an optional range.

Added better support for hinted note detection

Merge pull request #8 from mherrerarendon/peak

Use different library to implement peak finding

Added support for hinted note detection

Hinted note detection is useful when you need to detect if a specific note can be found within a signal, and the degree to which this specific note is in tune or not, among other things...