Abstract class for optical component added.

esbo_etc/classes/__init__.py

@@ -1,3 +1,4 @@
 from esbo_etc.classes.config import *
 from esbo_etc.classes.ITransmissive import *
-from esbo_etc.classes.target import *
+from esbo_etc.classes.target import *
+from esbo_etc.classes.optical_component import *

esbo_etc/classes/optical_component/__init__.py

@@ -0,0 +1 @@
+from esbo_etc.classes.optical_component.AOpticalComponent import *