Fixed errors with function definitions.

##### Now works in VS 2012: Debug and Release.

Changed function prototypes to ptorotypes from msdn: [EnumChildWindows function](http://msdn.microsoft.com/en-us/library/windows/desktop/ms633494%28v=vs.85%29.aspx), [EnumChildProc callback function](http://msdn.microsoft.com/en-us/library/windows/desktop/ms633493%28v=vs.85%29.aspx)