__main__ which is started if users starts optima35 without ui.

src/optima35/__main__.py

@@ -0,0 +1,8 @@
+from . import __version__
+
+def main():
+    print(f"optima35 (v{__version__}) is a core library and not intended to be run directly.")
+    print("Please use OptimaLab35 for a UI, run pip install OptimaLab35 and start with OptimaLab35.")
+
+if __name__ == "__main__":
+    main()