Finally updated all the things again

.
* new/updated stuff in USBNet
* The ScreenSavers hack now uses
libmobi instead of KindleUnpack for M7/KF8 files. I should have ported all the weird quirks I had to mangle KU with over the years, but do ping me if cover mode acts weird.
(Python is still required, because KFX).
* Hotfixes rebuilt for 5.13.1
Probably quite a few things I can't remember ;D.