more updates to preferences dialog and supporting code. almost done.

tools/lammps-gui/lammpswrapper.h

@@ -34,6 +34,8 @@ public:
     bool is_running();
     bool has_error() const;
     int get_last_error_message(char *errorbuf, int buflen);
+    bool config_has_package(const char *pkg) const;
+    bool has_gpu_device() const;
 
     bool load_lib(const char *lammpslib);
     bool has_plugin() const;