Apparently a 1 pixel margin works around Assassin's Creed buffer overlap misdetection

(while still keeping BOF working).

Should take care of #6599.
Add sanity checks to refuse to delete bad savedata (resulted in devastating delete of SAVEDATA/ in MGS PW!)

Thanks QWEmct for reporting in #6600.

This is not a full fix, really, a "NEW DATA" savegame should not show up in the delete list, but at least this prevents the bad thing from happening.
Non-windows buildfix
Only show button to delete savedata if there is savedata to delete
Regenerate font atlas
Update What's New in the README. If I forgot something big, comment on github or send a pull request.
More whatnew updates in the README
Update native with ES 3.1 detection on android
Qt: Use 'systeminfo' in Qt5 to disable screensaver.