Prevent reset the node color to the group color from storePositions function

[veredwpsemantix]

This pull request fixes the reset of node color when we call to storePositions function.

Example:
before storePositions:

after storePositions:

[Thomaash]

Hi @veredwpsemantix,

could you provide an MWE of the issue please? From what you posted this seems like a pretty serious issue in vis-data and should therefore be fixed there. What you provided is more of a hack around it (assuming I understand the problem correctly, which is difficult to gauge without an MWE).

Thanks and sorry for the atrocious response time

PS: There are JSFiddle and CodePen buttons on https://visjs.github.io/vis-network/examples/ to make MWE creation easier.