Add an option for wrapping too

On my machine, using a format without wrap (wrap = 0 in the test) and text with a line break causes
the bounds to be computed as a 2 pixel wide rectangle, only on ios.
Fix layout line bounds on ios

This wasn't adding the adjustX value, as explained in the class comment. It was also using the
height of the image bounds directly, which isn't really that useful for most applications.
Underlining would look weird because lines with no descending glyphs would have a smaller image
height and therefore a higher line position.