check for compatible LAMMPS version when creating LAMMPS instance

This check must be done at runtime, since the LAMMPS shared library
may have been loaded dynamically and thus required library functions
may not be present or missing features with too only a LAMMPS version.

tools/lammps-gui/lammpswrapper.cpp

@@ -36,6 +36,19 @@ void LammpsWrapper::open(int narg, char **args)
 #endif
 }
 
+int LammpsWrapper::version()
+{
+    int val = 0;
+    if (lammps_handle) {
+#if defined(LAMMPS_GUI_USE_PLUGIN)
+        val = ((liblammpsplugin_t *)plugin_handle)->version(lammps_handle);
+#else
+        val = lammps_version(lammps_handle);
+#endif
+    }
+    return val;
+}
+
 int LammpsWrapper::extract_setting(const char *keyword)
 {
     int val = 0;