(#383): bring glib and gio into the namespace.
Newer versions of rustc are able to figure out that we want
to use certain crates, and bring them into the namespace
from an imported prelude. But we need to still support
rustc 1.27+ and thus should explicitly use
the crates.
Attention
I haven't tested this change yet against rust 1.28, I don't have time at the moment to wait for the download. Will try to test it when it has finished in couple hours.
Close #383 (closed)