GTK+ renamed to GTK

The GTK+ toolkit project has, after extensive deliberation, decided to
remove the '+' from its name. 'Over the years, we had discussions
about removing the '+' from the project name. The 'plus' was added to 'GTK'
once it was moved out of the GIMP sources tree and the project gained
utilities like GLib and the GTK type system, in order to distinguish it
from the previous, in-tree version. Very few people are aware of this
history, and it's kind of confusing from the perspective of both newcomers
and even expert users; people join the wrong IRC channel, the URLs on wikis
are fairly ugly, etc.'