support write_ method on readonly param and more

- write method may be used internally on a readonly parameter
+ add IDLE, WARN, BUSY and ERROR to secop.core
+ secop.datatype.EnumType: allow 'self' as member name
+ secop.lib.statemachine: log Restart and Stop exceptions only on debug level
+ secop_psi.ccu4.CCU4: explicit conversion to float
+ secop.proxy: remove superfluos and erroneous make_secop_error

Change-Id: I2f13d31ceacd2bde65eab64f8eae4225556c18f5
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/27963
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/datatypes.py

@@ -22,7 +22,7 @@
 # *****************************************************************************
 """Define validated data types."""
 
-# pylint: disable=abstract-method
+# pylint: disable=abstract-method, too-many-lines
 
 
 import sys
@@ -454,7 +454,10 @@ class EnumType(DataType):
         super().__init__()
         if members is not None:
             kwds.update(members)
-        self._enum = Enum(enum_or_name, **kwds)
+        if isinstance(enum_or_name, str):
+            self._enum = Enum(enum_or_name, kwds)  # allow 'self' as name
+        else:
+            self._enum = Enum(enum_or_name, **kwds)
         self.default = self._enum[self._enum.members[0]]
 
     def copy(self):