Replaced the timing functions to take a function reference.

Only issues now is to somehow template the return type of the
function so that any function can be passed in for timing.
Added two helper functions to the Board class.

One is to see if the location on the board is empty.
The other function is to see if that piece is a king.

The function names are isEmpty, and isKing respectfully.
Added the ability to print the kings on the board.

Had to remove the constness from the printBoard function in the board
class due to having to construct a par to pass to the existence
functions.
Added further existence tests of the pieces on the board.

Added const to the existence functions. Have the simple moves created,
just need to work on the jump now. Also, need to check for bounds on the
move functions so that they do not reference memory that is not apart of
the board. Maybe need to add a buffer around to the board for this.