Don't have input widget loose focus after sending line to irb

The input widget is disabled while the input is evaluated by irb and
re-enabled after it finishes. This process makes the input widget loose
focus. Now this is avoided

plugins/irb/irb.rb

@@ -56,6 +56,7 @@ def initialize parent = nil
         @input.completion_mode = KDE::GlobalSettings::CompletionAuto
         @controller.connect SIGNAL(:ready) do
           @input.enabled = true
+          @input.set_focus if is_active_window
         end
         @ui.restart_irb.connect(SIGNAL(:clicked)) do
           @controller.restart_irb