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/proxy.py

@@ -23,8 +23,7 @@
 
 from secop.client import SecopClient, decode_msg, encode_msg_frame
 from secop.datatypes import StringType
-from secop.errors import BadValueError, \
-    CommunicationFailedError, ConfigError, make_secop_error
+from secop.errors import BadValueError, CommunicationFailedError, ConfigError
 from secop.lib import get_class
 from secop.modules import Drivable, Module, Readable, Writable
 from secop.params import Command, Parameter
@@ -47,8 +46,6 @@ class ProxyModule(HasIO, Module):
         if parameter not in self.parameters:
             return  # ignore unknown parameters
         # should be done here: deal with clock differences
-        if readerror:
-            readerror = make_secop_error(*readerror)
         self.announceUpdate(parameter, value, readerror, timestamp)
 
     def initModule(self):
@@ -201,7 +198,7 @@ def proxy_class(remote_class, name=None):
                 def wfunc(self, value, pname=aname):
                     value, _, readerror = self._secnode.setParameter(self.name, pname, value)
                     if readerror:
-                        raise make_secop_error(*readerror)
+                        raise readerror
                     return value
 
                 attrs['write_' + aname] = wfunc