~jaro/balkon

ref: a42dd23609b364bf2e4375d8205c1623e4155522 balkon/src d---------
Define BoxOptions and TextOptions for formatting.

Differentiating the two record types reflects the fact that the root
inline box cannot be styled but its text contents can.
Separate interface-independent layout algorithm.
Separate interface-independent constants.
Add user data to spans.
Use line numbers for page breaks.
Add line numbers to laid out fragments.
Future-proof records with options.
Fix compatibility with base < 4.15.
Improve terminology around fragments.
Fix documentation: missing Paginable.
Fix documentation: missing SpanOptions.
Fix documentation: document remaining names.
Fix documentation: export dependencies of exported names.
Fix documentation: incorrect reference.
Fix documentation: references to non-imported names.
Fix documentation: references to local names.
Separate internal plain Paragraph/ParagraphLayout.
Expose text slicing functions.
Decompose text slicing.
Integrate BiDi reordering.
Next