[mythtv] Check EDL length
[mythtv] Fix some french translations
[mythtv] New translations for future EDL dialogs
[mythtv] Add setting 'enable_edl'

- *Always
- Dialog
- Never
[mythtv] New classes to handle GUI dialog 'DialogYesNo'
[mythtv] Open dialog to enable/disable EDL for a show

Depending of the setting 'enable_edl', a dialog allow user to enable/disable EDL for the show.
[mythtv] WIN32: Add new sources in project

- guidialogbase.cpp
- guidialogyesno.cpp