traces update value part1: educationnal-objective/game-characters/game-context-game-educationnal-objective/mission-context/role/rules/step

Changes to the tutorial + Removal of conditions on prerequisites (adding a condition on tasks other than subtasks preventing subtask prerequisites) + Addition of a condition for a unique common task symbol in a role + Fix clean-dialog text

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