Added public files

Roughly added all public files. Probably missed some, though.
diff --git a/doc/materials/groups/MATGROUP_WOOD b/doc/materials/groups/MATGROUP_WOOD
new file mode 100644
index 0000000..5466d1d
--- /dev/null
+++ b/doc/materials/groups/MATGROUP_WOOD
@@ -0,0 +1,5 @@
+Gruppenid:
+MATGROUP_WOOD
+
+Name:
+Hoelzer