fixed bug in FW_dev2image() that prevented icon retrieval for "0" states

git-svn-id: https://fhem.svn.sourceforge.net/svnroot/fhem/trunk/fhem@1921 2b470e98-0d58-463d-a4d8-8e2adae1ed80

FHEM/01_FHEMWEB.pm

@@ -2209,7 +2209,7 @@ FW_dev2image($)
   return "" if(!$name || !$d);
 
   my ($type, $state) = ($d->{TYPE}, $d->{STATE});
-  return "" if(!$type || !$state);
+  return "" if(!$type || !defined($state));
 
   my (undef, $rstate) = ReplaceEventMap($name, [undef, $state], 0);
   $state =~ s/ .*//; # Want to be able to have icons for "on-for-timer xxx"