Remove r_flashlightscissor (and do it cleanly)
* It was already disabled in-engine and was duplicated in model rendering, but did basically nothing if enabled, and was always disabled on game start anyway.
Remove FCVAR_ARCHIVE from sv_skyname
* Since it is reset on map load every time anyway, even on dedicated servers.
Remove r_raindensity (unused)
Remove Logitech G15 integration leftovers
* We never shipped the .dll for it work, so I think it was always unusable, so just get rid of it entirely.
* Removes associated g15 convars
Remove HL2 start new game dialog code, more XBox UI stuff
* It was already made inaccessible prior, but now removed entirely.
Convar adjustments
* Made `adsp_debug`, `cl_debugrumble` a cheat, remove archive flag
* Added a bunch more archived convars to Lua blocklist
* Remove mat_norendering, add descriptions to some other `mat_` convars so they can be found with `find`.
Remove HL2 game logo and menu buttons code, console animations
Update TTT - Linux font swap
Added more FCVAR_Archive cvars to Lua blocklist
* Replaced a few ARCHIVE flags with CHEAT flags for debug convars (scene_show* for example)
* Removed r_drawvgui, vgui_message_dialog_modal
* Removed sv_unlockedchapters, stop reading `scripts/ChapterBackgrounds.txt`