implement cursor moving functionality

[nnyyxxxx]

dont merge

includes initialization of cursor moving functionality from #29 , and fully implements it

closes #29

[nnyyxxxx]

#34 needs to be reworked,

        self.buffer.chars[BUFFER_HEIGHT - 1][self.column_position].write(ScreenChar {
            ascii_character: b' ',
            color_code: self.color_code,
        });

will not work properly here.

[nnyyxxxx]

#34 needs to be reworked,

        self.buffer.chars[BUFFER_HEIGHT - 1][self.column_position].write(ScreenChar {
            ascii_character: b' ',
            color_code: self.color_code,
        });

will not work properly here.

disregard this, fixed in a20603c

[nnyyxxxx]

ded