The goal is to catch cases where the return value exists, but is
forgotten. There was a large enough number of them to turn this
into a real check. Initially, I just wanted to implement it to fix
the problems, then delete the code. But since this is so common, I
think it is worth the annoyance.
This way their name doesn't get mangle by the broken magic. It will also
eventually allow to `error()` in the template when the implicit
`@function` is used.
This commit also fixes a large number of issues found while
proof-reading everything.
Given they are all small, it makes more sense to just merge them like
we did for the client API
For some reasons GTK doesn't want to be merged. To be investigated.
Emmanuel Lepage Vallee
Alphonse Mariya
actionless
Uli Schlachter