Test handling of empty lines.
Make RTL text overflow the left paragraph edge.
This behaviour is consistent with CSS Text Module Level 3.
BREAKING: Previously, all text would overflow the right paragraph edge,
regardless of text direction.
Fix handling of mixed line height.
Displace lines by the height of the tallest fragment in the previous
line, not the shortest one.
Remove paragraphLineHeight from Rich interface.
Test ultra narrow Arabic text.
Test unions of lists of rectangles.
Expose rect unions in public interface.
Implement unions of lists of rectangles.
Parametrise rectangle union bias.
Remove TODO which would require an API break.
Test shaping across intra-word breaks.
Set release date for v1.1.0.0.
Simplify code since run direction is always known.
Add TODO for end-of-line whitespace.
Update changelog on numbers and neutrals.
Improve BiDi handling of numbers and neutrals.
Autodetect text direction for legacy interface.