Smart Camera Update: Track Mouse Click

I added an update to the smart camera to allow it to track where you
click the mouse button. This will determine where the camera will then
move to. See main.cpp.
Smart Camera Update: Track Click-Drag

I have added support for the click-drag feature of the smart camera.
This works by clicking and holding your custom mouse button and then
dragging it to pan. This is just like Google Maps.
Updated README.md and Changed the Demo Map