Fix documentation of ProtoFragment after RTL placement.
Insert extra test to work around segmentation fault.
Without the added test, the test suite causes a segmentation fault
after starting "wraps by characters when line is ultra narrow".
Add line wrapping tests with spans.
Implement correct positioning of RTL runs.
Make SpanOptions a separate type.
Slightly decompose the Plain module.
Update documentation and derived instances.
Expose ParagraphConstruction.
Hide Rect union from public interface.
The function behaves in a specific way that should not be relied on by
other modules.
Use internal library to hide non-public modules.
Move non-public modules into Internal namespace.
Represent line breaks directly without offsets.
Make ParagraphConstruction more efficient.
Make paragraphRect origin always 0,0.
This convention should make it easier for the caller to properly place
the paragraph within a document.
Fix mistakes in documentation comments.
Remove unnecessary default implementation.