Removed several files, lots of redundancy, and still need to add event loop
I need to be more reliabe with my commits. See previous commit for description. This is just a fix of the previous commit
Re-added the event file, change how AppStates are constructed, made a changestate function
Renamed Event to SFMLEvent.

Removed SFMLEvent.cpp (no longer needed.)
SFMLEvent is a 100% vitual base class.
added Application::OnEvent. Calls the appropriate event function in state.
AppState inherits SFMLEvent
AppStateGame inherits SFMLEvent.

Defined AppStateGame ctor.
Example implementation of OnLButtonPressed
fixed up chesspp::exception to inherit std::exception.
Enabled vertical sync for the display.