margin in mat-menu / new tooltips / replace purger by effacer / fix add role dialog message  / zoomin and zoomout with buttons / click on a piece show details + remove icon button to show detail / set font-family everywhere

fix: prerequires panel no longer close automatically + clear task now clear the prerequires too + clear role now clean the prerequired ressources in tasks

change app language to french + add upload and download files + connect game-context and game-educationnal-objective to the model