IDE+Runtime: fix exception when reconnecting with non-empty trace/force list.

Sometimes, remote call to SetTraceVariableList returned None just after reconnecting:
- changed caller to accept None (in case of connection problem)
- changer SetTraceVariable list to return 4 (DEBUG_SUSPENDED) if debug is suspended

<?xml version='1.0' encoding='utf-8'?>
<BeremizRoot xmlns:xsd="http://www.w3.org/2001/XMLSchema" URI_location="PYRO://127.0.0.1:61427">
  <TargetType/>
  <Libraries Enable_SVGHMI_Library="true"/>
</BeremizRoot>