Merge branch '712-trying-to-load-a-folder-as-an-addon-causes-a-bad-cycle-error-everytime' into 'next'

Resolve "[2.2.10 prerelease] Trying to load a folder as an addon causes a "bad cycle" error every time"

Closes #712

See merge request STJr/SRB2!2412

SPR2defaults fix

See merge request STJr/SRB2!2461

Fix spriteinfo indexing

Closes #1255

See merge request STJr/SRB2!2463

Fix #1248

Closes #1248

See merge request STJr/SRB2!2452

Fix 3D floor side texture scaling (resolves #1247)

Closes #1247

See merge request STJr/SRB2!2435

Fix FOFs with transferline flag and many linedefs randomly crashing

See merge request STJr/SRB2!2285

Prevent infinite loop in R_RenderThickSideRange

See merge request STJr/SRB2!2470

Fix 3D floor side texture scrolling (resolves #1215)

Closes #1215

See merge request STJr/SRB2!2392

Ignore flats when loading patches

See merge request STJr/SRB2!2457

Fix repeatcnt data type mistake in UDMF specification

See merge request STJr/SRB2!2458

Fix players not rendering on team scoreboards

See merge request STJr/SRB2!2460

Fix Ctrl+Backspace in the console causing a crash

See merge request STJr/SRB2!2437

Fix Linedef type 466

Closes #1246

See merge request STJr/SRB2!2453

Fix #1222

Closes #1222

See merge request STJr/SRB2!2448

Fix composite "flats as patch" name overlap crash

See merge request STJr/SRB2!2450

Fix keyboard input when certain keys overlap with dead keys

Closes #1174

See merge request STJr/SRB2!2443

Like with ccache, we want to make sure the git checkout is considered
clean during build.

Placing these directories at the root will make the git revision
detection consider the working directory to be dirty.

Fixes: KartKrew/Kart#1405

The "clone" strategy clones the entire repository, which takes
a significant amount of time. It's not needed, because the default
"fetch" strategy will reuse the executor's local clone and clean it
before the job scripts run.

There's no need to let these artifacts pile up since the only ones that
will be relevant to non-programmers are the latest from any given ref.

Ring Racers' object file output is considerably larger than SRB2.
50M is insufficient to hold even a single build.

The singular .gitlab-ci.yml is pretty beefy. Splitting it into
smaller files by job and job template will make maintaining the
individual jobs easier.