Patch by Jean-François Massol

a few fix in fr.po

(SETUP without Transport:)

isrc/Makefile.am: Include media_list_path.h to fix make dist-clean, as requested by j-b and aballier.

Qt4 - Podcast dialog: Don't use the default OK/Cancel buttons, because they wouldn't be translated if we do it the default way. This does almost the same output. 

Qt4 - Right click on the header on the QTreeView for the playlist enables you to choose the columns you want to be shown. This removes also the code that was in the Model part since this is View Related. Ref #1282 (almost done).
There is still segfaults on close of VLC after that menu is triggered.

wxwidgets: fix crash in playlist due to change in meta behaviour (all metas used to retunr "" rather than NULL)