Trying to follow GLib/GTK+ best practices for the order of includes

Refactored includes to follow the glib best practices:
 * config.h (if required) * own module header file
 * system header files
 * required headers from current project

Inspoired on https://bugzilla.gnome.org/show_bug.cgi?id=735887
Equalizer dialog not need PraghaApplication.
The filter dialog either need PraghaApplication.
Remove useless option to setting gstreamer version.

Was readded by mistake on commit d54ce8c8
PraghaPreferencesDialog not depend on PraghaApplication.

Some changes are automatic, and others depend on accept or cancel the dialog. That it is better?
Merge branch 'master' into debian
1.3.1+git20141121-1