`plot` syntax should be closer to ggplot2

[mschubert]

because consistency is good, everyone should know the ggplot2 syntax anyway, and we most likely couldn't come up with anything better

maybe also provide "bare bone" plotting objects where users can exchange the data

[zslastman]

Worth noting that hadley is moving away from ggplot2 and toward ggvis, so ggplot2 may soon not be the de-facto standard it is now.

[mschubert]

I doubt this will happen to productive level any time soon - and syntax is similar, so more a question of moving to using the grammar.

But good point mentioning.