make tracebox respond to negative-skin ents, in addition to the built-in pmove code, so mods should now be able to detect it properly.
work around a believed issue with ericw-qbsp's skip texture support - if an invalid surface is referenced, don't try to generate decals from it.
players blinking in and out of view in latest 5186
fixed in 5196
fix r_waterstyle 2/3 entity flickering
fix r_wateralpha in the d3d9+d3d11 renderers too.
fix r_nolerp stutter bug.
xinput tweaks, under advice from primallove.