fixed issue: interfaceFilter not taking effect in interfaceTableVisua…

…lizer #1004

The omnetpp matcher expression parser currently acceppts only the " for quoting:
  "quoted" parsed to >>>quoted<<<
  'quoted' parsed to >>>'quoted'<<<

showcases/visualizer/canvas/interfacetable/omnetpp.ini

@@ -13,7 +13,7 @@ description = "Advanced features"
 *.configurator.config = xmldoc("config.xml")
 
 *.visualizer.interfaceTableVisualizer.displayInterfaceTables = true
-*.visualizer.interfaceTableVisualizer.interfaceFilter = "not lo* and not ipv4Address =~ '<unspec>'"
+*.visualizer.interfaceTableVisualizer.interfaceFilter = 'not lo* and not ipv4Address =~ "<unspec>"'
 
 *.router.hasDhcp = true
 *.router.dhcp.interface = "eth1"