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New Flag

* Add no `--no-values` flag to suppress the display of ending values

Code Quality

* Codestyle fixes in 64 props to dmitriy-0297
* Add exception check for rading file 63 props to dmitriy-0297

Release Notes

- Fix incompatibility bug with label_before args undefined (57)
- Fix min/max with multiple categories props to MaximeVdB (56)

Adds a new flag `--label-before` that displays the labels in front of the lines, not the end.
Props to wgxo for the contribution.

Note: When using the `--label-before` flag, you may also want to use `--format={:7.2f}` or something similar so the labels right-align instead of the default left-align.

- Fix issue two graphs not showing when using `--different-scale` flag 49
Props to HiromuIshikawa

* 38 Support Python >= 3.6
* 40 Fix stacked label alignment

* PR 31 - Fix to normalize method, division by zero error. Props to ocozalp

* PR 32 - Fix vertical graphs, missing args. Props to joaquincasares

* PR 32 - Do not output color character if not specified. Props to joaquincasares