Chordparser

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* Reorganised code folder structure
* Changed note structure to be split into letter and symbol
* Added ``get_letter_intervals`` method to NoteEditor
* Refactored tests to have more of a single responsibility

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* Fixed empty README author (fixes failed build - PyPI could not read the README)

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* **FAILED BUILD**
* Fixed empty README description
* Fixed Sphinx documentation for readthedocs

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* **FAILED BUILD**
* Included ``transpose_simple`` method to only use semitones for transposing
* Included initial Sphinx documentation

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* Removed code with static typing
* Removed unused instance variables in classes
* Changed ``Note.symbolvalue()`` to ``Note.symbol_value()`` for namespace consistency
* Include ``Note.letter_value()`` method
* Fixed wrong errors being raised
* Refactored scale building code
* Abstracted chord quality to a separate Quality class
* Quality now includes sus chords, Chords no longer have a ``Chord.sus`` attribute
* Refactored chord notation regex parsing for methods to be reusable
* Abstracted roman numeral notation to a separate Roman class, and roman conversion to a separate ChordRomanConverter class

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* Changed song in sample_sheet.cho
* Added ability to remove all added notes
* ``incl_submodes`` defaulted to False in analysing chords