[qmf] Add QT_NO_MESSAGE_SERVER_EDITOR to remove widgets dependency

QtWidgets was loaded by messageserver5 and the other main libraries,
which is unnecessary and wastes RAM.

This also removes the qmfutil package (used only be examples) and the
examples package, as those were widgets applications and aren't built
when the flag is set.
Merge pull request #40 from special/remove-widgets

[qmf] Add QT_NO_MESSAGE_SERVER_EDITOR to remove widgets dependency