[Eric] File opening default filter

[Stjujsckij Nickolaj]

> It is on the Editor->Filehandling page. Please be aware, that it has no  
> effect on Linux systems using a KDE dialog wrapper for Qt because KDE  
> dialogs work different from Qt dialogs. In that case, you should disable  
> the usage of these wrappers (unfortunately I don't know how) or use the  
> wrappers of eric4 (if PyKDE4 is installed). The internal wrappers handle  
> the filter preselection right.
  If anyone on the list knows how to disable KDE-style dialogs in Eric (and  
in other pure-Qt apps too), please share the knowledge. I'm positively  
loath those, and Eric can't handle their filetype filters... I have got  
rid of PyKDE and rebuilt everything I found (PyQt-related stuff) without  
KDE support, but they are still here to bug me. Seems like I should  
install PyKDE again and try to make use of Eric dialog wrappers for it.