Don't draw effect rings w/gravgun equipped.

[StrawWagen]

I get why this was a feature, since the gravgun can pick up, move effects.

But I'm gonna be straight, nobody places, moves effects with the gravgun, it's a weapon you use to "play the game".
If I'm wrong, and someone does use the gravgun to place effects, I feel very confident saying they're vastly outnumbered by the players who use it solely as a weapon.

"cl_draweffectrings 0" does exist, but it's not the "default player experience", it's another, albeit very small, "barrier to entry".

Thanks for considering this very small PR, for what I feel is an equally small oversight.

[robotboy655]

Making prop_effect invisible with the gravity gun would also imply that it should not interact with them, if we are to apply gameplay logic here.

[StrawWagen]

Yeah, but my opinion is there's more people fighting with the gravity gun, than people using it to interact with effects.

This change is really just for the small save/course building community.
It sucks to make an elaborate course with cool details everywhere, only for a bunch of yellow circles to show up when you give players the best half life 2 weapon haha.