Fixed missed g_free in command_run_string.
Removed vb_set_mode from the commands.

This mode switching is only used if the commands are called from inputbox most
of the time and not if called via keybindings. So we can skip the function
calls for keybinds and do it in command_run_string instead.
Fixed no more working counts for key commands.

Another way to avoid access to destroyed widget. Don't destroy the widgets
explicitly, this makes the gtk for us.