Package ui is now only about units except for the Config.Now method.
Remove Now and rename Config to Converter. Add layout.Config to
replace the old ui.Config.
Signed-off-by: Elias Naur <mail@eliasnaur.com>
Text shaping is a common name for what package measure does. Rename
it to "shape" and move it below the text package.
Signed-off-by: Elias Naur <mail@eliasnaur.com>