- Initialize the kpsewhich QProcess in the fontLocate() method
- Remove the usage of fontProgressDialog and use the warning
  signal to notify the user on the status of font generation.
- The change makes it "easier", in future, to kill the font
  generation when the user opens a new document. Right now it
  is not possible to stop the generation.

Reviewed by: Albert Astal Cid, Fabio d'Urso
(and thanks for the hints!)