Add support to Wilkinson's graphic algebra

[ThamaluM]

• [ ] I have searched the issues of this repository and believe that this is not a duplicate.

What problem does this feature solve?

The varset algebra in Wilkinson's grammar of graphics (cross, nest and blend) provide an efficient way to handle facets. It makes codes consize than writing command for every facet view.

What does the proposed API look like?

e.g.

chart.line().position(string) where string can be like cross: a*b nest: a/b blend: a b

Cross will represent a point for every (a,b) point crossing domains. Nest will represent a point (a,b) only when there is a json containing corresponding both a,b values. Blend will simply draw two chars in same plane at once wothout repeating same command twice. See Wilkinson's chapter in grammar of graphics for more details.

[ThamaluM]

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[ThamaluM]

1692 has been entered again

[ThamaluM]

1692 has been entered again

[ThamaluM]

1692 has been entered again