[Feature] Courtroom slides - Based once again

[in1tiate]

Refactor of #869, now with 70% fewer merge conflicts.

Took the old code verbatim and added pair support,. As far as my testing shows, this kinda just works.

Formatting required for setup:

Full courtroom image (should be named "court.png" but can work with any name)
Design.ini parameters:

[court:def]
pos_center=320
slide_ms_pro=550
slide_ms_wit=500

[court:wit]
pos_center=1467
slide_ms_pro=500
slide_ms_def=500

[court:pro]
pos_center=2614
slide_ms_def=550
slide_ms_wit=500

where "court:pos" is the main image and the name of its subposition.
pos_center is the pixel position of the center of the part of the image you want to be a position
and the transition duration settings are formatted as slide_ms_pos and a duration in milliseconds.

Additionally, there is support for giving characters a special pose during transitions if an "Objection!" shout was used.

[Options]
objection_pose = pointing

This PR also adds a checkbox to the main UI to enable or disable sending the new MS parameter SLIDE which dictates whether a message is able to trigger a slide animation.

Additionally, a global setting is now in the settings menu to disable slide animations for yourself.

---

Rebased from #959.

[TrickyLeifa]

The format has been updated to the following:

scaling = smooth
positions = wit2

[court:def]
rect=0, 0, 640, 384
slide_ms_pro=550
slide_ms_wit=500

[court:wit]
rect=1147, 0, 640, 384
slide_ms_pro=500
slide_ms_def=500

[court:pro]
rect=2294, 0, 640, 384
slide_ms_def=550
slide_ms_wit=500

Biggest difference is that instead of a position in space it's a rect that covers the background.

[Salanto]

Improves Performance
Improves readability
Improves functionality
Improves improvements

After some testing of regular AO2 animation behaviour frameFX and co seem to work correctly too. No reason to wait any longer.
(The side logic is looking worse for wear, but that should be overhauled in another branch/PR)