Flit-core backend for pure python builds (#71)

update lock

update readme and lock

v6.0.0

and fixes

Drop python 2.7 support (#52)

Fix image urls

use secret

Examples, text, markers, ellipse, ... (#39)

* Add examples.
* Allow marker characters for plot and scatter.
* Allow to write text inside the canvas.
* Add ellipse and circle data generation.
* Add vertical and horizontal lines for figures.
* Add vertical and horizontal rectangles for figures.
* Allow to customize X and Y ticks via callbacks.
* Improve docs.
* Respect NO_COLOR and FORCE_COLOR.