Fix for throwing knives when using noblock

[azalty]

This patch fixes #51

There are probably other methods but I think this one is a good compromise:

Original issue:

• The knife is a smokegrenade_projectile, which makes it physics based
• Using noblock makes players not solid, making the knife go through them instead of hitting them. It's pretty weird because I think it started for me after the nades update (or maybe it was when I enabled noblock, can't remember). From my testing, it seems the knife CAN hit a player but only at weird angles, and pretty rarely

The fix:

• We create a trigger_multiple that is 10x10 units at the same time as the knife, we put it at the same position and set the knife as parent. This will make the trigger move with the knife
• Once the trigger is triggered, we check that it is a player and if yes, we emulate the knife collide function.
• The knife will kill the player as before, and will also kill the trigger with itself

Feel free to adjust values and so, I didn't calculate trigger bounds that much, but as far as I see, it works perfectly in game!

Specificities:

• We don't emulate the knife collide function directly to prevent the knife from instantly lowering its despawn delay to 1.0 (see default code), as the trigger can spawn inside the thrower
• A new global int variable is created to store the number of thrown knives from the start of the round, because we need to set a unique targetname to each knife, to set it as parent -> throwknife_%i", g_iKnifesCounter (starts from 0, reset every round start)
• It will trigger this warning every time a knife is thrown: Setting CBaseEntity to non-brush model models/error.mdl. Sadly I can't do anything about it
• I'm unsure if I need to precache models/error.mdl or no. I didn't get any crash whereas while I chose another model, it crashed. I'm assuming it means no.

Credits: https://forums.alliedmods.net/showthread.php?t=129597 and other posts about parenting entities and collision groups

[azalty]

Cases where knife still goes through guards have been reported on my server. I think the trigger might not be high enough, because it only seems to happen when we aim down. I'll try to scale it better, even though these cases happen rarily.

Also, you can apparently get hit if the knife is thrown on a thin wall, and you are close to the wall. This makes sense because the trigger can actually go through walls. Again, this will be fixed when the trigger is scaled properly.

It shouldn't be a big problem anyways, not a giant priority to fix that. You might want to add a cvar to make people able to enable/disable it if they have noblock

[azalty]

Seems like it might be needed to precache models/error.mdl as it could be not precached by default. It was not needed on my server, but I got a crash report from someone running a CS:S server (running the standalone throwingknives plugin without MyJailshop). Precaching this model fixed the crash.

Simple code to add to fix this crash UTIL_SetModel: not precached: models/error.mdl:

public void OnMapStart()
{
    PrecacheModel("models/error.mdl");
}