Disable vertex attrib arrays in overlay_gl (fixes #1298)

This is a fix for the OpenGL overlay which disables
and enables the vertex attrib arrays inside drawContext.
The problem it fixes is that some games leave some of
the arrays enabled between frames, which I think
(not an OpenGL expert) causes the input to the vertex
shader to essentially be arbitrary.
Transifex translation update

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Update WoW Plugin to build 19034

Update WoW plugin, including switching to 128-bit GUIDs, which I've
naively done with a structure containing two 64-bit integers instead.
There's probably a nicer way to do this.
Update Opus to version 1.1.1 beta

Fixes #1439
Fix crash on Linux when trying to configure shortcuts.

Trying to set a push-to-talk key Xlib functions were
called before the display and thus Xlib functions being
initialized, leading to a crash concerning /dev/input.
Debug output:

 #0  XKeycodeToKeysym (dpy=0x0, kc=50 '2', col=0) at ../../../src/xkb/XKBBind.c:111

This patch calls XOpenDisplay() earlier to avoid this.

Fixes #1250
Transifex translation update
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Fix Qt 5 transition bug making certificate wizard access out of bounds.

Unfortunate typo which made us access empty string instead of the
guaranteed non-empty list we wanted to fill the string from.
Make AudioInputDialog and AudioOutputDialog use own icons.

Introduced config_audio_input.png and config_audio_output.png
for for that. Previously used config_basic.png.

Part of #1438
Drop unused files and icon.

Seems like we had some unreferenced files lying around.
- PAAudioConfig seems to be an (unfinished?) PulseAudio
  configuration dialog.
- PositionalSound seems to be an (unfinished?) positional
  audio configuration dialog.

They both used the config_dsound.png (directional? directsound?)
which this commit also drops as it doesn't seem to be used
anywhere.
Revert recent installer changes as they create more issues than they fixed.

This reverts commits e7282052993602ae5e0a1d3a8485c17adbf89d50
and 1749ef46dfc4c9ead4e41766ba9cace786f4fa35 .
Merge remote-tracking branch 'upstream/master'