build: Include enum-types.[ch] in the introspection sources

Otherwise g-ir-scanner won't pick the types up, and will not notice that
the error enumerations have an associated error domain.

https://bugzilla.gnome.org/show_bug.cgi?id=730917
Release JSON-GLib 1.0.2
Post-release version bump to 1.0.3
[l10n] Update Catalan translation