Prints character on the screen at specified coordinate.
VGA.printchar( x, y, c, trans )
x - x coordinate of the screen where the character is to be displayed
y - y coordinate of the screen where the character is to be displayed
c - character to be displayed
trans - if transparent, trans is true, else false
//prints the word "HELLO"
VGA.printchar(0, 0, 'H' );
VGA.printchar(0, 1, 'E' );
VGA.printchar(0, 2, 'L' );
VGA.printchar(0, 3, 'L' );
VGA.printchar(0, 4, 'O' );