* In-game timer option! Doesn't tick in intermission or in lag, only when a frame is actually run. Realtime option remains default.
* Tweak retry behaviour to restart timer and not subtract life if you're on the first level and haven't hit a checkpoint yet.

Remove emblem hints from Marathon Run (I think Options is good just for the sake of live events, though).

Introducing "antisplice" - a pair of small highlights on the Marathon bar that is based on the real time the executable has been open for and *isn't* restored with the Live Event Backup, making spliced runs basically intractable.

Make live event backup files savedata specific (new format: `live%s.bkp`, where %s is the time attack folder name/savegame name - so vanilla's is `livesrb2sav.bkp`).

# Conflicts:
#	src/doomdef.h

Add carry types to Dust devils

See merge request !886

Introducing Marathon Run. (I was going to call it Marathon Mode, but NiGHTS Mode being right next to it on the menu looked terrible.)

Basically a dedicated Record Attack-like experience for speedrunning the game as a continuous chunk rather than ILs. Has several quality of life features.

Benefits include:
* An unambiguous real-time bar across the bottom of the screen, always displaying the current time, ticking up until you reach the ending.
* Disable the console (pausing is still allowed, but the timer will still increment).
* Automatically skip intermissions as if you're holding down the spin button.
* Show centiseconds on HUD automatically, like record attack.
* "Live Event Backups" - a category of run fit for major events like GDQ, where recovery from crashes or chokes makes for better entertainment. Essentially a modified SP savefile, down to using the same basic functions, but has its own filename and tweaked internal layout.
* "spmarathon_start" MainCfg block parameter and "marathonnext" mapheader parameter, allowing for a customised flow (makes this fit for purpose for an eventual SUGOI port).
* Disabling inter-level custom cutscenes by default with a menu option to toggle this (won't show up if the mod doesn't *have* any custom cutscenes), although either way ending cutscenes (vanilla or custom) remain intact since is time is called before them.
* Won't show up if you have a mod that consists of only one level (determined by spmarathon_start's nextlevel; this won't trip if you manually set its marathonnext).
* Unconditional gratitude on the evaluation screen, instead of a negging "Try again..." if you didn't get all the emeralds (which you may not have been aiming for).
* Gorgeous new menu (no new assets required, unless you wanna give it a header later).

Changes which were required for the above but affect other areas of the game include:
* "useBlackRock" MainCFG block parameter, which can be used to disable the presence of the Black Rock or Egg Rock in both the Evaluation screen and the Marathon Run menu (for total conversions with different stories).
* Disabling Continues in NiGHTS mode, to match the most common singleplayer experience post 2.2.4's release (is reverted if useContinues is set to true).
* Hiding the exitmove "powerup" outside of multiplayer. (Okay, this isn't really related, I just saw this bug in action a lot while doing test runs and got annoyed enough to fix it here.)
* The ability to use V_DrawPromptBack (in hardcode only at the moment, but) to draw in terms of pixels rather than rows of text, by providing negative instead of positive inputs).
* A refactoring of redundant game saves smattered across the ending, credits, and evaluation - in addition to saving the game slightly earlier.
* Minor m_menu.c touchups and refactorings here and there.

Built using feedback from the official server's #speedruns channel, among other places.

Act number tweaks

See merge request !905

Fix window icon being reset when switching renderers on non-Windows platforms

See merge request STJr/SRB2!898

Fix OpenGL only recording the first frame of unoptimized GIFs

See merge request STJr/SRB2!928

GCC 10 compiling fixes

See merge request STJr/SRB2!937

added missing extern keyword for ms_RoomId in mserv.h (the definition is already in the .c file in this case)

turn all non-extern variables in s_sound.h into externs (and put their real definitions in the .c file)

Fix splitscreen Title Card act name regression

See merge request STJr/SRB2!934

Menu soc bullshit mergefix

See merge request STJr/SRB2!933

2.2.4 preparation

See merge request STJr/SRB2!935

Fix crash with rollout rock

See merge request STJr/SRB2!936

This fixes act names not being shown on player 2's view

Don't show the FPS counter during startup.

See merge request STJr/SRB2!930

Fix Simple Camera not working with the tutorial's statue challenge

See merge request STJr/SRB2!931

Fix the BotRespawn hook and hooking A_Dye being disabled for no reason

See merge request !932

Merge branch 'master' of https://git.magicalgirl.moe/STJr/SRB2.git into fickleheart/SRB2-menu-soc-bullshit

# Conflicts:
#	src/m_menu.c