add wood and forest roles

ml/fml40/roles/dts/forest/forest.py

+from ml.ml40.roles.dts.dt import DT
+
+
+class Forest(DT):
+    def __init__(self, name="", identifier=""):
+        super().__init__(
+            name=name,
+            identifier=identifier)

ml/fml40/roles/dts/forest/forest_segment.py

+from ml.fml40.roles.dts.forest.forest import Forest
+
+
+class ForestSegment(Forest):
+    def __init__(self, name="", identifier=""):
+        super().__init__(
+            name=name,
+            identifier=identifier)

ml/fml40/roles/dts/forest/tree.py

+from ml.fml40.roles.dts.forest.forest import Forest
+
+
+class Tree(Forest):
+    def __init__(self, name="", identifier=""):
+        super().__init__(
+            name=name,
+            identifier=identifier)

ml/fml40/roles/dts/woods/WoodPile.py

+from ml.fml40.roles.dts.woods.wood import Wood
+
+class WoodPile(Wood):
+    def __init__(self, name="", identifier=""):
+        super().__init__(
+            name=name,
+            identifier=identifier)

ml/fml40/roles/dts/woods/stem_segment.py

+from ml.fml40.roles.dts.woods.wood import Wood
+
+class StemSegment(Wood):
+    def __init__(self, name="", identifier=""):
+        super().__init__(
+            name=name,
+            identifier=identifier)

ml/fml40/roles/dts/woods/wood.py

+from ml.ml40.roles.dts.dt import DT
+
+class Wood(DT):
+    def __init__(self, name="", identifier=""):
+        super().__init__(
+            name=name,
+            identifier=identifier)