Support for calc function.

[TadeasKriz]

It would be nice if we could do some calculations in the stylesheet. For example I have a constant called @gridStep and I would like to do something like cornerRadius: calc(@gridStep * 2);. Currently I could not find a way to do this in ISS. Is it possible? Or would that feature be possible to add? Thanks.

[tolo]

Yes, that would be nice, and I have actually though a bit about this in the past (for instance when implementing ISSLayout). It shouldn't be too hard to add I think, so I will definitely look into doing that for the next feature release.