Merge pull request #260 from Loop3D/fix/add-observer

fix: add an observer/notify datastructure

Author: lachlangrose

.flake8

@@ -20,6 +20,7 @@
 loggers = {}
 from .modelling.core.geological_model import GeologicalModel
 from .modelling.core.stratigraphic_column import StratigraphicColumn
+from .modelling.core.fault_topology import FaultTopology
 from .interpolators._api import LoopInterpolator
 from .interpolators import InterpolatorBuilder
 from .datatypes import BoundingBox