Thorsten Simon

The error occurs using the cmap method of the palette for matplotlib: ``` from colorspace import heat_hcl pal = heat_hcl() pal.cmap() ``` I guess adding ``` self._rev = False ```...

I just forked the repo and added [this line](https://github.com/meteosimon/python-colorspace/blob/8922dfbe25c014a98b6ac744337f1e47f623e332/colorspace/palettes.py#L1653), it now seems to work, no error, specplot is identical to [R's colorspace](https://colorspace.r-forge.r-project.org/). BTW: `terrain_hcl()` would need the same fix.