I have a couple problem with these commands.

First, the name of this command says to add next/previous *line* to selection, but it only adds a *cursor*. This seems weird to me. Are we following the functionality of some other editor? I suppose it's helpful if you plan to issue editor commands that operate on whole lines even if line is only partially selected, but that's not the only way to use multiselection.

Second, if you select an entire line and execute `addNextLineToSelection` then cursor is not added to next line, but line after that. From a technical standpoint I understand why this happens, but is it what user wants/expects? This is same issue as `deleteLine` deleting 2 lines instead of 1 with a line selected.