Take steps towards "fixing" keyboard input

The file 'Include\fixrk.h' contains the new function
`CorrectRawKeyboardInput`.

[As described in this article][1], Win32 does not return particularly
viably complete information about keyboard data in a `RAWKEYBOARD`
structure. This means   that the structure needs to be _corrected_.

It is important to notice the type of `CorrectRawKeyboardInput` is a
return of `CONST RAWKEYBOARD` and a parameter of `CONST RAWKEYBOARD`.
This makes the functions __pure__. The function is authored this way
because of the [arguments made in this article][2].

   [1]: http://molecularmusings.wordpress.com/2011/09/05/properly-handling-keyboard-input/ "Properly handling keyboard input"
   [2]: http://www.altdevblogaday.com/2012/04/26/functional-programming-in-c/ "Functional Programming in C++"