~jaro/balkon

ref: 397a9e427f251005c29846c94299ef5d6467d352 balkon/lib/Data/Text d---------
Better format ParagraphConstruction documentation.
Separate module for the ParagraphLayout type.
Remove (~) operator from ParagraphConstruction.

The tilde operator was causing compilation errors with older versions
of GHC, possibly due to a conflict with the lazy pattern match syntax.

It has been replaced by a pure Haskell alternative that uses function
application.
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.