mint-arena: Move SnapVectorTowards to bg_misc.c
mint-arena: Add [c]g_unlagged.c from Unlagged 2.01 GPL
mint-arena: Change [c]g_unlagged.c license headers
mint-arena: Add [c]g_unlagged.c to the build system
mint-arena: Remove static from some cgame functions for Unlagged
mint-arena: Add g_unlagged.c function prototypes
mint-arena: Port g_unlagged.c to this codebase

Also, add some of the gplayer_t fields and disable cg_unlagged.c
so "make BUILD_UNLAGGED=1" can compile.

Based on changes made by @ChicagoPraiseTheDarknessDev.
mint-arena: Add unlagged backward reconciliation function calls
mint-arena: Fix unlagged TeleportPlayer

Call G_ResetHistory after updating r.currentOrigin.
mint-arena: Fix unlagged PlayerSpawn

Call G_ResetHistory after updating ent->s.mins/maxs.
Clearing player->saved.leveltime is done with the player is memset to 0.
mint-arena: Add full lag compensation option
mint-arena: Remove UNLAGGED define
mint-arena: Rename player position history vars to ET names
mint-arena: Fix set by unused warnings in g_unlagged.c
mint-arena: Add Lag Compensation to q3_ui's network menu
mint-arena: Revert Unlagged G_RunMissile changes

Requires CGame changes (projectile nudging) that haven't been added yet.
I'm unsure if this is desireable, for default game play at least.