Change the way that DrawText parses the next line to display, ready to

Change the way that DrawText parses the next line to display, ready to
support multiline ellipsification etc.  Rather than measuring the text
each time we add a character and breaking once it is too long and
WORDBREAK is enabled, we copy a whole text segment and then measure
it; GetTextExtentPointEx is designed to tell us how much fitted.  This
may result in a little rescanning if wordbreak is enabled but will be
well worth while when multiline path ellipsification is brought down
into the NextLine function.  Note also that the wordbreak calculation
is a little more complete (e.g.  including break-within-word for
DT_EDITCONTROL).