ENABLE_3DCONNEXION_DEVICES - 1st installment of support for 3Dconnexion devices

Implemented using hidapi library (https://github.com/libusb/hidapi) and https://github.com/koenieee/CrossplatformSpacemouseDriver/tree/master/SpaceMouseDriver as reference

Unsolved issues:

- When manipulating the SpaceNavigator wxWidgets generates a mouse wheel event that needs to be filtered out

- wxWidgets does not detect devices being connected/disconnected to the pc

- Current state forces a continuous rendering

- Current state misses dependence on camera zoom

- Non intuitive movement limits

- Translation and rotation speed factors are hardcoded

- Number of device buttons hardcoded

src/slic3r/GUI/Plater.hpp

@@ -41,6 +41,7 @@ class ObjectSettings;
 class ObjectLayers;
 class ObjectList;
 class GLCanvas3D;
+class Mouse3DController;
 
 using t_optgroups = std::vector <std::shared_ptr<ConfigOptionsGroup>>;
 
@@ -251,6 +252,10 @@ public:
     void msw_rescale();
 
     const Camera& get_camera() const;
+#if ENABLE_3DCONNEXION_DEVICES
+    const Mouse3DController& get_mouse3d_controller() const;
+    Mouse3DController& get_mouse3d_controller();
+#endif // ENABLE_3DCONNEXION_DEVICES
 
 	// ROII wrapper for suppressing the Undo / Redo snapshot to be taken.
 	class SuppressSnapshots