Parametrize fillMode for .useColumns
Parametrize fillMode for .useColumns

A @fillMode parameter for .useColumns9) allows setting 
`column-fill` property to `balance` for wide statblocks (or other
wide column types) instead of relying on Chrome's fallback
behavior that ignores `auto` when there's no set container height.
Set the default for the for `@fillMode` to `auto` to maintain the
current behavior.
calculuschild/homebrewery,calculuschild/homebrewery