Include fixity information in the Interface file

This resolves fixity information not appearing across package borders.

The binary file version has been increased accordingly.
Update changelog
Update appearance of fixity annotations

This moves them in-line with their corresponding lines, similar to a
presentation envision by @hvr and described in #ghc.

Redundant operator names are also omitted when no ambiguity is present.
Filter family instances of hidden types

Currently, this check does not extend to hidden right hand sides,
although it probably should hide them in that case.
Add documentation for --source-entity-line