include some custom composite examples in satpy

It would be great to implement some custom composite examples as known from mpop documentation.
Nice would be the custom .yaml file(s) with the changes in generic.cfg for this composites:
natural [1.6], [0.8], [0.6]
overview [0.6], [0.8], [10.8] and a
severe storms ( R : VIS0.8 Range : 0-100 [%]-Gamma : 1.0, G : VIS0.8 Range : 0-100 [%]-Gamma : 1.0, B : IR10.8-IR3.9 Range : -60 - -40 [K]Gamma : 2.0), and a
clouds convection (R : VIS0.8 Range : 0-100 [%]-Gamma : 1.0, G : VIS0.8 Range : 0-100 [%]-Gamma : 1.0, B : IR10.8 Range : 323-203 [K]-Gamma : 1.0

and the same with HRV channel (luminance):
HRV-overview [HRV] ... ,HRV natural, HRV severe storms, HRV clouds convection.
A simple code example to render with euro1 area all custom composites should be provided.

Maybe the number of examples could be reduced and some of this composites added as defaults?
Some HRV composites could be available as fixed composites in satpy.
BTW. the snow reflecatnce composite seems not implemented any more (was present in mpop)?

Regards,

Christian