fix some remaining py3 incompatibilites

- None <= 0  is invalid in py3
- restrict BLOBType to bytes (may be changed after migration to py3)
- remove long
- use list(<dict>.items()) when dict is changed within loop
- allow initialization of properties in HasProperties without
  supercall to base class
- <dict>.values() can not be indexed
- adapted/removed various tests. additional tests might be added
  after definitive migration to py3

after this change, all the tests run with py3, also secop-server and
secop-gui were tested with an example, but other code might still contain
py3 incompatibilities

Change-Id: I881c6972aeabb8494a21a6cbc7ffeddfd4f5d4f8
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/21306
Tested-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>
Reviewed-by: Bjoern Pedersen <bjoern.pedersen@frm2.tum.de>

secop/lib/enum.py

@@ -70,7 +70,7 @@ class EnumMember(object):
     def __eq__(self, other):
         if isinstance(other, (EnumMember)):
             return other.value == self.value
-        if isinstance(other, (int, long)):
+        if isinstance(other, int):
             return other == self.value
         # compare by name (for (in)equality only)
         if isinstance(other, (str, unicode)):
@@ -178,8 +178,6 @@ class EnumMember(object):
         return self.value.__invert__()
     def __int__(self):
         return self.value.__int__()
-    def __long__(self):
-        return self.value.__long__()
     def __float__(self):
         return self.value.__float__()
         #return NotImplemented  # makes no sense