original use of "legacy" meshColor

[mdsumner]

now we need to decide, is meshColor by default

-[ ] vertices, a color value on 'material$color' for every column in 'vb' -[ ] faces, a color for every column in 'ib/it' -[ ] legacy, expanded color repeated for each vertex for 'faces' (this is what quadmesh expaects now)

this example, depends on legacy for example:

https://gis.stackexchange.com/a/237309/1204

I'm inclined to go for faces, since 'quad mesh' but need a closer look