LCD library for noka 3110 display
Date: 27 Oct 2009
Author: A Lindsay
Credits: based on original nuelectronics library extensively tidied up
and with functions re-named and recoded.
Additional graphics code added with options to disnable graphics if
not required, see nokia_3110_lcd.h

Updated: 10th November by John Crouchley
1) Allow for multiple SPI devices by
   a) allowing SPI_CS to reside on any port
   b) set SPCR as part of LCDENABLE
2) move get_key into the class
3) Fix bug in writeChar caused column 6 of any character not to be updated
4) add code to ensure values for cursor_row and cursor_col are kept within array bounds
5) Inherit Nokia_3310_lcd class from Print and add a write function
   This enables all normal print behaviour, including numbers

Updated: 14th November by Andrew Lindsay
1) Create new big font that is cleaner.

Updated: 9th December 2009 by John Crouchley
1) PORTB2 (Arduino digital 10) must be set to OUTPUT and HIGH whilst SPCR is being changed
   Failure to do this can lead to intermittent SPI errors.
   If there is another SPI device already using PORTB2 then it will naturally be high already
   Warning - if you use this pin for anything else (other than another SPI device enable)
   then you may have problems.

Updated: 26th January 2010 by John Crouchley
1) Initialisation values (contrast and temp coefficient) updated for later LCDs (got a black screen)
   values taken from updated driver on Nuelectronics site. This still works with the earlier lcds.

Updated: 2nd September 2010 by Andrew Lindsay based on changes supplied
by jmccrohan to add extra characters to big_font