I've long wondered why dialogs seem to update twice when it seems
they just need to update once. It seems it was this code. But it
was only put there to deal with a problem with code in the button
controllers that was disabled in 2007! So I'm going to try removing
it. If we start seeing weird behavior with dialogs in master, then
this will be why.
In particular, the directory frontends/qt4 is renamed to frontends/qt.
Many configurations file have to be updated. All mentions of qt4 in
the source have been audited, and changed to qt if necessary.
The only part that has not been updated is the CMake build system.
