- Ambiguous `raw_value()` method is replaced with `line_number()` and
`span()`.
- `line_name()` that before returned either line name or area name is
replaced with `line_name()` and `area_name()`.
- `Position` type is replaced with `Line` and `Area` type so we don't
have to guess while doing layout.
Affected test expectations:
- `template-lines-and-areas` - improvement over what we had before.
- `named-tracks` - rebaseline a giant test. will have to split it into
smaller tests in the future.
c03e025a32