Add support for new chat colors (#379)

* Add backwards-compatible support for new chat color system

* Use default

* Set LangVersion properly

* Add backwards compatible ctors in TorchChatMessage

* Fix not setting Font if it's not MyFontEnum

* Use correct color mappings

Torch.API/Utils/StringUtils.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Reflection;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Torch.Utils
+{
+    /// <summary>
+    /// Utility methods for strings
+    /// </summary>
+    public static class StringUtils
+    {
+        /// <summary>
+        /// Determines a common prefix for the given set of strings
+        /// </summary>
+        /// <param name="set">Set of strings</param>
+        /// <returns>Common prefix</returns>
+        public static string CommonPrefix(IEnumerable<string> set)
+        {
+            StringBuilder builder = null;
+            foreach (string other in set)
+            {
+                if (builder == null)
+                    builder = new StringBuilder(other);
+                if (builder.Length > other.Length)
+                    builder.Remove(other.Length, builder.Length - other.Length);
+                for (var i = 0; i < builder.Length; i++)
+                    if (builder[i] != other[i])
+                    {
+                        builder.Remove(i, builder.Length - i);
+                        break;
+                    }
+            }
+            return builder?.ToString() ?? "";
+        }
+
+        /// <summary>
+        /// Determines a common suffix for the given set of strings
+        /// </summary>
+        /// <param name="set">Set of strings</param>
+        /// <returns>Common suffix</returns>
+        public static string CommonSuffix(IEnumerable<string> set)
+        {
+            StringBuilder builder = null;
+            foreach (string other in set)
+            {
+                if (builder == null)
+                    builder = new StringBuilder(other);
+                if (builder.Length > other.Length)
+                    builder.Remove(0, builder.Length - other.Length);
+                for (var i = 0; i < builder.Length; i++)
+                {
+                    if (builder[builder.Length - 1 - i] != other[other.Length - 1 - i])
+                    {
+                        builder.Remove(0, builder.Length - i);
+                        break;
+                    }
+                }
+            }
+            return builder?.ToString() ?? "";
+        }
+
+        private static string[] FontEnumValues => _fontEnumValues ?? (_fontEnumValues = typeof(VRage.Game.MyFontEnum).GetFields(BindingFlags.Public | BindingFlags.Static).Where(x => x.IsLiteral && !x.IsInitOnly).Select(x => (string)x.GetValue(null)).ToArray());
+
+        private static string[] _fontEnumValues;
+        public static bool IsFontEnum(string str)
+        {
+            return FontEnumValues.Contains(str);
+        }
+    }
+}