Style: Cleanup uses of double spaces between words

Or after punctuation. Tried to leave third-party stuff alone, unless it has
been heavily modified for Godot.

core/math/quick_hull.cpp

@@ -112,7 +112,7 @@ Error QuickHull::build(const Vector<Vector3> &p_points, Geometry3D::MeshData &r_
 		}
 	}
 
-	//fourth vertex is the one  most further away from the plane
+	//fourth vertex is the one most further away from the plane
 
 	{
 		real_t maxd = 0;