graphe + dijkstra ok

...java/com/example/myhabitat/CreationOuvertureActivity.java

app/src/main/java/com/example/myhabitat/MainActivity.java

...in/java/com/example/myhabitat/ModeConceptionActivity.java

app/src/main/java/habitat/Piece.java

app/src/main/java/outils/GrapheHabitat.java