Deduplicate pagination functions in Editor and BrewRenderer

[G-Ambatte]

As per this comment on PR #2162, with the merging of that PR, the pagination function in the BrewRenderer will be duplicated in the Editor.

It should be possible to use React.cloneElement to add props to the this.props.children (as identified in this comment) being handled in SplitPane.jsx to pass a unified pagination function as a prop to both child elements.