removal of legacy "returns" blcoks with next gtk-doc release

[Stefan Sauer <ensonic hora-obscura de>]

hi,

for legacy reasons gtk-doc accepted documenting the return value by
starting a line with "Returns" (not Returns:") [1]. This of course can
be ambiguous and thus is not recommended. Normally one can disambiguate,
by having a proper Returns: block. Still this can cause trouble for void
functions [2].

My proposal is that project check their docs and fix these. I will
remove legacy support in git in the coming days and that will be in the
next gtk-doc release then (1.19 - no eta yet).

Stefan

[1] http://git.gnome.org/browse/gtk-doc/tree/gtkdoc-mkdb.in#n3936
[2] https://bugzilla.gnome.org/show_bug.cgi?id=678094