Minor Update: Menus, Polish and a Bug Fix.

Added :

1. Game now loads to main menu, instead of directly to the play stage.
2. Credits Screen on main menu.
3. Background music on main menu and play stage.
4. Pause menu ( press Escape [ Esc ] or Backslash [ \ ]).

Fixed :

1.  Fixed a bug requiring double click for lifting objects with click and drag, after navigating from the main menu to the play stage.