build3d TCanvas Support — Feature Request

[danielch02]

Would it be possible to extend the build3d function to support TCanvas?

Use case:
TCanvas object could be passed directly as a parameter to build3d, the function would then return the corresponding TCanvas as a 3D object.

Note:
Although a TCanvas can contain multiple object types and, in principle, support could be added for all objects that can be rendered in 3D, as discussed we can initially limit this functionality to 1D histograms.

[linev]

#375 will implement build3d for TCanvas