Redo character's hit points modifiers

So it doesn't just randomly say, 'Stuff'.

Also, have I rolled health for level 14? The total seems too low.
Fix bug with arrow-navigation in mod list

When the Row migrated to a RowLayout, some of its dependent
properties (like Positioner.index) weren't updated.

I haven't found a replacement, so I've hardcoded the values for
now. Will fix later.
Fix up initiative

My character never actually took Improved Initiative - I just
completely forgot about my familiar.
Add a confirmation dialog before quitting

Since it's going to contain quite a few volatile values, I don't
want a fumbling of hotkeys to make me loose everything.