Add Style configuration

The following functionalities are added to configure aerc ui styles.
- Read stylesets from file with very basic fnmatch wildcard matching
- Add default styleset
- Support different stylesets as part of UiConfig allowing contextual
  styles.
- Move widgets/ui elements to use the stylesets.
- Add configuration manual for the styleset

commands/msg/move.go

@@ -71,7 +71,7 @@ func (Move) Execute(aerc *widgets.Aerc, args []string) error {
 		case *types.Done:
 			aerc.PushStatus("Message moved to "+joinedArgs, 10*time.Second)
 		case *types.Error:
-			aerc.PushError(" " + msg.Error.Error())
+			aerc.PushError(" "+msg.Error.Error(), 10*time.Second)
 		}
 	})
 	return nil