Merge dev branch

* Cherry-pick failed, so just made my own version of the commit "sortable uses intersect rather than pointer" since it was a single line of code change
* Excludes column resizing work, which will be developed separately and not on a dev branch
* Needs review (I haven't looked yet, and will review and make changes on this branch) - some of these commits are old.

@bigsley @yayalice @ldevalliere