Previously, the row offsets were hardcoded to the ones used for 20x4
displays (which woudl also work for all 2-line displays). Now, the
number of columns given is used to calculate the offsets most likely to
apply.
For 2-line displays and 20x4 displays, the (used) offsets are completel
unchanged. With this change, common 16x4 displays and (if they even
exist) other 4-line and 3-line displays might also work (depending on
the hardware configuration used, of course).
See this page for some info on common LCD sizes and configurations
encountered in practice:
http://web.alfredstate.edu/weimandn/lcd/lcd_addressing/lcd_addressing_index.html
Before, the row value was maximized against _numlines already, but the
value from _numlines is not limited anywhere, so it could be longer than
the length of _row_offsets. This check makes sure the array bounds is
never exceeded.
