#4 PLC peripheral disconnect handling and small bugfixes/cleanup

scada-common/log.lua

@@ -34,6 +34,10 @@ function _debug(msg, trace)
     end
 end
 
+function _info(msg)
+    _log("[INF] " .. msg .. "\n")
+end
+
 function _warning(msg)
     _log("[WRN] " .. msg .. "\n")
 end

scada-common/ppm.lua

@@ -90,7 +90,7 @@ function handle_unmount(iface)
     
     log._warning("PPM: lost device " .. type .. " mounted to " .. iface)
 
-    return self.mounts[iface]
+    return lost_dev
 end
 
 -- list all available peripherals