Changing dot size in scatter plots

[sahands]

Is this currently possible to do in a nicer way than what I have below?

plot.marks[0].marks[0].properties.enter.size.value = DOT_SIZE

[jaredly]

Looks like it's hard-coded atm. Would be a good pull request.

https://github.com/wrobstory/vincent/blob/master/vincent/charts.py#L183

        enter_props = PropertySet(
            x=ValueRef(scale='x', field="data.idx"),
            y=ValueRef(scale='y', field="data.val"),
            size=ValueRef(value=100),  # <-- right here
            fill=ValueRef(scale="color", field='data.col'))