numberformat:'d' prevents display in tooltip for numbers with decimal places

[wahlatlas]

Using numberFormat:'d' in the meta definition allows only integers to be displayed in the .hoverInfotooltip, whereas numbers with decimal places are not displayed at all, not even their label. This can currently be worked around with numberFormat:'0f'

[floledermann]

Formatting Strings are passed through to d3.format, which is implemented this way ("use Number.toString, but ignore any non-integer values")

I added a note in the documentation, though.