APC & SMES appearances. (#78)

* CEV-Eris SMES sprite as RSI.

Has been modified so that the light overlay states use alpha blending.

* Add tiny glow to SMES display sprite.

* Appearances work v2

* More WiP

* RoundToLevels works correctly on even level counts now.

* SMES -> Smes because MS guidelines.

* CEV-Eris APC sprite.

* APC visuals.

* Reduce SMES scale again to normal levels.

* Update submodule

Content.Tests/Shared/Utility/ContentHelpers_Test.cs

@@ -0,0 +1,60 @@
+using Content.Shared.Utility;
+using NUnit.Framework;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Content.Tests.Shared.Utility
+{
+    [Parallelizable]
+    [TestFixture]
+    [TestOf(typeof(ContentHelpers))]
+    public class ContentHelpers_Test
+    {
+
+        public static readonly IEnumerable<(double val, double max, int levels, int expected)> TestData = new(double, double, int, int)[]
+        {
+            // Testing odd level counts. These are easy.
+            (-1, 10, 5, 0),
+            ( 0, 10, 5, 0),
+            ( 0.01f, 10, 5, 1),
+            ( 1, 10, 5, 1),
+            ( 2, 10, 5, 1),
+            ( 2.5f, 10, 5, 1),
+            ( 2.51f, 10, 5, 2),
+            ( 3, 10, 5, 2),
+            ( 4, 10, 5, 2),
+            ( 5, 10, 5, 2),
+            ( 6, 10, 5, 2),
+            ( 7, 10, 5, 2),
+            ( 7.49f, 10, 5, 2),
+            ( 7.5f, 10, 5, 3),
+            ( 8, 10, 5, 3),
+            ( 9, 10, 5, 3),
+            (10, 10, 5, 4),
+            (11, 10, 5, 4),
+
+            // Even level counts though..
+            ( 1, 10, 6, 1),
+            ( 2, 10, 6, 1),
+            ( 3, 10, 6, 2),
+            ( 4, 10, 6, 2),
+            ( 5, 10, 6, 2),
+            ( 6, 10, 6, 3),
+            ( 7, 10, 6, 3),
+            ( 8, 10, 6, 4),
+            ( 9, 10, 6, 4),
+            (10, 10, 6, 5),
+        };
+
+        [Parallelizable]
+        [Test]
+        public void Test([ValueSource(nameof(TestData))] (double val, double max, int levels, int expected) data)
+        {
+            (double val, double max, int levels, int expected) = data;
+            Assert.That(ContentHelpers.RoundToLevels(val, max, levels), Is.EqualTo(expected));
+        }
+    }
+}