Move KeyboardBehavior into main so that it can control multi graphics
Enable switch feature on KeyboardBehavior
Hide KeyMap in implementation, not exposed in header.
Let KeyboardBehavior controls scenery and graphical mesh separately.
CppLint warning fix
Another way to register graphics representations with a key.
Use template to register graphics representations in KeyboardBehavior.
Clean up source code, remove unnecessary std::algorithms, revise comment
Revise keyboard registration steps.
Add time filter to suppress possible multiple calls to update
the keyboard for each single key pressed.
Pre-allocate the memory for m_keyRegister and using static_pointer_cast.