Fix event unlistening in gmf-featurestyle
Fix event unlistening in gmf-featurestyle

ger-benjamin/ngeo,pgiraud/ngeo,camptocamp/ngeo,camptocamp/ngeo,Jenselme/ngeo,kalbermattenm/ngeo,pgiraud/ngeo,kalbermattenm/ngeo,Jenselme/ngeo,adube/ngeo,ger-benjamin/ngeo,Jenselme/ngeo,Jenselme/ngeo,pgiraud/ngeo,camptocamp/ngeo,camptocamp/ngeo,kalbermattenm/ngeo,camptocamp/ngeo,adube/ngeo,adube/ngeo,ger-benjamin/ngeo,adube/ngeo