Add additional text file extensions (mostly for IdTech 3 and GoldSrc)

[SirYodaJedi]

Added formats are as such (mostly for making PK3s easier to navigate):

• .log - self explanatory; one is found in Quake III's pak0.pk3.
• .config - used in Quake 3 for defining multiplayer gamemode cvars (same syntax as cfg and rc)
• .sc - GoldSrc weapon scripts (unused in vanilla)
• .mat - Condition Zero Deleted Scenes particle effects, Quake II Remaster footstep sfx, Fairytale Busters VMT (unrelated formats, but all plain text)
• .shader - IdTech 3 materials
• .skin - IdTech 3 skin remaps (similar syntax to CSV)
• .arena - IdTech 3 map metadata
• .script - RtCW and WolfET scripts (probably also used elsewhere)
• .objdata - WolfET per-map cvars (same syntax as cfg and rc)
• .icarus - Raven software uncompiled script (various IdTech 3 games)
• .efx - Raven software particle effect (various IdTech 3 games)

Some of the formats are similar to KeyValues, I guess, but I didn't touch keyValuesLikeFormats since I don't know what qualifies there (apparently .map doesn't?).
Draft because I don't know if modifying SingleFile.h is necessary.

[SirYodaJedi]

(btw, the readme mistakenly claims that PK3 is a Quake II format instead of a Quake III format; Q2 uses the same PAK format as Q1 and HL1. Didn't change this, but it probably should be fixed.)

[craftablescience]

(btw, the readme mistakenly claims that PK3 is a Quake II format instead of a Quake III format; Q2 uses the same PAK format as Q1 and HL1. Didn't change this, but it probably should be fixed.)

Oh yeah this is a typo lol

[craftablescience]

.mat is also used in Fairy Tale Busters as a replacement for the .vmt extension despite being identically formatted