Automatic merge of X1.3.1-195-g6502efe3d and 8 pull requests

- Pull request #40 at e81861b: Monogame upgrade
- Pull request #79 at 7d9f14b: Update version calculation for new unstable versions
- Pull request #216 at 927a49c: Upgrade and replace web server with EmbedIO
- Pull request #226 at 26983e9: EmbedIO web server graphical track monitor
- Pull request #227 at 6ec1539: EmbedIO web server graphical train driving monitor
- Pull request #228 at 72c0146: adds links to OR on Elvas Tower
- Pull request #232 at 699c09a: JSON consist format: https://blueprints.launchpad.net/or/+spec/consist-editor
- Pull request #234 at 3ac34fe: Rehabilitate unit testing suite, migrate to xUnit 2

Source/ORTS.Common/TrainFile.cs

@@ -225,10 +225,15 @@ public static string ResolveEngineFile(string basePath, string[] subFolders, str
         /// <returns>All files with known train or consist file extensions.</returns>
         public static IEnumerable<string> AllTrainFiles(string basePath)
         {
-            ISet<string> BaseNames(string directory, string pattern) => new HashSet<string>(
-                Directory.GetFileSystemEntries(directory, pattern)
-                    .Select((string path) => Path.GetFileNameWithoutExtension(path)),
-                StringComparer.InvariantCultureIgnoreCase);
+            ISet<string> BaseNames(string directory, string pattern)
+            {
+                if (!Directory.Exists(directory))
+                    return new HashSet<string>();
+                return new HashSet<string>(
+                    Directory.GetFileSystemEntries(directory, pattern)
+                        .Select((string path) => Path.GetFileNameWithoutExtension(path)),
+                    StringComparer.InvariantCultureIgnoreCase);
+            }
 
             ISet<string> ortsBaseNames = BaseNames(Path.Combine(basePath, "trains", "lists"), "*.train-or");
             ISet<string> mstsBaseNames = BaseNames(Path.Combine(basePath, "trains", "consists"), "*.con");