scrollcellintoview fix (see https://github.com/joshq00/SlickGrid/commit/cea2e55929f07e1f38c722b929e7f8afe0275296)
Add pgUp pgDn functionality (see https://github.com/joshq00/SlickGrid/commit/991c3ab6e1ef77b814b82bed113942809039fc26)
Fix for paging and scrolling (see https://github.com/joshq00/SlickGrid/commit/f3181205c951538e5122247754fd15f43dc90a3f)