Fix non-ascii workspace rename via menu

Fix non-ascii workspace rename via menu

As pointed out in the comments in

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=304480

it's not possible to rename workspaces with non-ascii characters -- more
precisely characters which require deadkeys with your particular keyboard.

According to the investigation made by Rodolfo Peñas:

http://lists.windowmaker.org/dev/msg02529.html

the fundamental issue behind this bug is the fact that XLookupString can't
handle deadkeys.

So either we do something radical or live with the bug.

However -- as Rodolfo also pointed out -- renaming the workspaces via the
Clip works with non-ascii chars. The reason is that the Clip uses a input dialog
function from WINGs to handle the renaming.

So instead of doing the low-level handling of text inside the menu in order
to rename workspaces, just fire up the same WINGs input dialog to handle it.
It works and the old function editEntry() can be removed.

Furthermore, it makes the whole set of functions in src/wtext.c useless, and
they are removed in the next patch.

Overall, 600 lines of code are gone now.

Signed-off-by: Carlos R. Mafra <crmafra@gmail.com>