Better default size for the setting dialog
Make remember the size of the settings dialog

Before, we saved the geometry in the closeEvent which is only called if
the user press the [x] in the title bar.  But it is not called when the
user accept the dialog (by pressing the close button or the enter key)
So save the geometry in the destructor of the dialog instead.

One also must call delete from the Application destructor because it was
leaking
Fix saving the geometry of the log browser