ReadHandler and WriteHandler decorators

modules with a couple of parameters with similar read_* or
write_* methods may handle them by generic methods wrapped
with decorators ReadHandler / WriteHandler

The trinamic driver is included in this change for demonstrating
how it works.

In a further step, the special handling for the iohandler stuff can
be moved away from secop.server and secop.params, using this feature.

+ fix problem on startup of trinamic driver (needs MultiEvent.queue)
+ some other small fixes
+ apply recommended functools.wraps for wrapping

Change-Id: Ibfeff9209f53c47194628463466cee28366e17ac
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/27460
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/io.py

@@ -86,7 +86,7 @@ class IOBase(Communicator):
     uri = Property('hostname:portnumber', datatype=StringType())
     timeout = Parameter('timeout', datatype=FloatRange(0), default=2)
     wait_before = Parameter('wait time before sending', datatype=FloatRange(), default=0)
-    is_connected = Parameter('connection state', datatype=BoolType(), readonly=False, poll=REGULAR)
+    is_connected = Parameter('connection state', datatype=BoolType(), readonly=False, default=False, poll=REGULAR)
     pollinterval = Parameter('reconnect interval', datatype=FloatRange(0), readonly=False, default=10)
 
     _reconnectCallbacks = None
@@ -95,6 +95,7 @@ class IOBase(Communicator):
     _lock = None
 
     def earlyInit(self):
+        super().earlyInit()
         self._lock = threading.RLock()
 
     def connectStart(self):