Merge pull request piermorel#60 from trallard/patch-tania

Reorganised sections to make the Readme clearer

Preparation for JOSS submission

Preparation for JOSS submission

Added customization options for text, lines and points

- Added set_line_options(): style, size
- Added set_point_options(): markers, size
- Added set_text_options(): font, sizes
- Corrected bug with iscategorical() on old matlab versions

Added functionality to manipulate legend axes

Corrected rare error on y limit computation. Simplified code in draw()