Update Marlin/ultralcd_implementation_hitachi_HD44780.h

Fix to a minor bug with hardcoded LCD_WIDTH that draws edited values outside of the 16 characters width LCDs.
Update Marlin/ultralcd_implementation_hitachi_HD44780.h

Use all available characters in narrow LCDs < 20 characters.
Merge pull request #389 from mfeherpataky/Marlin_v1

Update Marlin/ultralcd_implementation_hitachi_HD44780.h