Correctly detect next selected slide when deleting a slide in PowerPoint's thumbnails view. Fixes #3415.

Specifically:
 * bind documentwindow's selectionChange script to delete and backspace.
 * Slide NVDAObject's name property: catch COMError when fetching slideNumber (this was already done for title)
minHook is now included as a git submodule. You must do a git submodule update to fetch it the first time.
User Guide: Screen Review: Remove the word "deepest".

It's technically accurate, but confusing for new users. The idea should be clear enough anyway; it wouldn't make sense to move to the shallowest object.
PowerPoint app module: changeSelection script: Don't bother trying to handle the change if there is a script waiting.

This improves performance when rapidly pressing or holding down keys that change the selection.
displayModel: don't accidentally inforce a final blank line at the bottom of all displayModel TextInfos. Re #3425.
Merge branch 'master' of git://git.nvaccess.org/nvda into jpbranch