Propagate BiDi levels to layout algorithm. BREAKING: Text direction of the root box is now correctly used for ordering fragments. Previously, the order was always LTR.
Move BiDi Level to separate module.
Integrate BiDi reordering.
Fix style: white space in exports and imports.
Decompose ProtoFragment construction.
Fix documentation of ProtoFragment after RTL placement.
Implement correct positioning of RTL runs.
Move non-public modules into Internal namespace.
Lay out Runs independently of Spans.