Split Editor and Runtime into separate namespaces, Created Texture and Mesh classes

Runtime/PSXMesh.cs

@@ -0,0 +1,13 @@
+using UnityEngine;
+
+namespace PSXSplash.RuntimeCode {
+
+    [System.Serializable]
+    public class PSXMesh {
+        public bool TriangulateMesh = true;
+
+        public void Export() {
+            Debug.Log($"Export: {this}");
+        }
+    }
+}