Dataswim

Feature release: new methods:

`gmean_` to group by + mean

`scolor_` to get a unique color from a predefined serie

`mline_` and `mpoint_` to draw a multiple line charts from a colum's values

`sarea_` and `sbar_` to draw stacked charts

`arrow_`: adds an arrow pointer in a chart

`sline_` chart to get a smooth line between a serie of points

`map_` to support maps with Folium

`

Bugfix release: fix version import in setup

Bugfix release: fixes an error in `_trimquants`

Bugfix release: add missing dependency

Feature release + bug fixes.

New methods: `subset`, `diffm`, `load_excel`, `load_json`, `merge`, `resetall`, `ratio`, `gsum_`, `lreg`

Add the diffn method