Remove peek from page leaf merge.
Remove peek from page leaf merge.

Remove peek at the right sibling leaf page of the right leaf page  of a
leaf page merge. This method no longer being called. We've been ignoring
that peek for longer than the last commit which claimed to begin to
ignore it.

See #187.

bigeasy/strata,bigeasy/strata,cesarmarinhorj/strata,cesarmarinhorj/strata