several improvements and bugfixes

+ rework GUI
  - include a combobox for selection of visibility
  - include a checkbox wether validation should be done in the client
  - remove unused lineEdit
+ improve datatypes
+ improve tests for new descriptive data
+ metaclasse: fix overlooked read_* or write_* func's
+ improve polling
+ Introduce new ErrorClasses
+ dispatcher: use new features of datatypes + PARAMS
+ improve lib
+ autopep8
+ first working version of MLZ_entangle integration
+ split specific stuff into it's own package (MLZ,demo,ess)

Change-Id: I8ac3ce871b28f44afecbba6332ca741095426712

secop/errors.py

@@ -33,3 +33,11 @@ class ConfigError(SECoPServerError):
 
 class ProgrammingError(SECoPServerError):
     pass
+
+
+class CommunicationError(SECoPServerError):
+    pass
+
+
+class HardwareError(SECoPServerError):
+    pass