Test layout with mixed font sizes.

Prepare for test modules sharing font options.

Fix style: small Prelude imports.

Fix style: white space in exports and imports.

Fix data types in harfbuzz-pure.

Add shaped runs for demo.

Allow custom font options outside FontLoader.

Add test for Devanagari.

Add test for RTL text.

Add explicit scale to test font.

Separate tests by module.