Merge MathHelper and FloatMath

Requires  space-wizards/RobustToolbox#1234

Content.Client/UserInterface/CooldownGraphic.cs

@@ -41,7 +41,7 @@ namespace Content.Client.UserInterface
             }
             else
             {
-                var alpha = FloatMath.Clamp(0.5f * lerp, 0f, 0.5f);
+                var alpha = MathHelper.Clamp(0.5f * lerp, 0f, 0.5f);
                 color = new Color(1f, 1f, 1f, alpha);
             }