Parsing `f3d::colormap_t` by name

[michaelmigliore]

Is your feature request related to a problem? Please describe.
Currently, it's only possible to parse colormap by value and color lists.
See function colormap_t parse(const std::string& str) in options_tools.h.

Describe the solution you'd like
However, when colormap presets are available, we should be able to parse by name.
For example, it should be possible to type in the console: set model.scivis.colormap viridis

[mwestphal]

That requires some applicative logic to be moved to library, I'm not sure we want that.

[Meakk]

It feels like it would be a very good feature for libf3d apps. I'm thinking of the web app where I'd love to have a combox with named colormaps.

[mwestphal]

It feels like it would be a very good feature for libf3d apps. I'm thinking of the web app where I'd love to have a combox with named colormaps.

Indeed, that would be nice, but it means that all colormaps should be embedded in the lib and not shipped as files as they are now.