removed old style syntax

- removed secop/metaclass.py
- moved code from ModuleMeta to modules.HasAccessibles.__init_subclass__
- reworked properties:
  assignment obj.property = value now always allowed
- reworked Parameters and Command to be true descriptors
- Command must now be solely used as decorator
- renamed 'usercommand' to 'Command'
- command methods no longer start with 'do_'
- reworked mechanism to determine accessible order:
  the attribute paramOrder, if given, determines order of accessibles
+ fixed some issues makeing the IDE more happy
+ simplified code for StatusType and added a test for it

Change-Id: I8045cf38ee6f4d4862428272df0b12a7c8abaca7
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/25049
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/core.py

@@ -29,11 +29,10 @@
 from secop.datatypes import FloatRange, IntRange, ScaledInteger, \
     BoolType, EnumType, BLOBType, StringType, TupleOf, ArrayOf, StructOf
 from secop.lib.enum import Enum
-from secop.modules import Module, Readable, Writable, Drivable, Communicator, Attached
+from secop.modules import Module, Readable, Writable, Drivable, Communicator, Attached, Done
 from secop.properties import Property
-from secop.params import Parameter, Command, Override, usercommand
+from secop.params import Parameter, Command
 from secop.poller import AUTO, REGULAR, SLOW, DYNAMIC
-from secop.metaclass import Done
 from secop.iohandler import IOHandler, IOHandlerBase
 from secop.stringio import StringIO, HasIodev
 from secop.proxy import SecNode, Proxy, proxy_class