Implemented new modes. Tweaked getText() method.

MODE_ROLL1 and MODE_ROLL2 have been implemented.
The getText() method has been modified to account for the terminating
NULL character at the end of the char array. The toCharArray() method
now uses sizeof(char[]) instead of a static value. LCD.clear() has been
commented out, since it causes visible flicker whenever an LCD update is
called. The code will need to be further modified to ensure that the
previously displayed text is completely overwritten with either the new
text or blank spaces, else the previous text will persist partially on
the LCD.