Merge pull request #515 from slingamn/issue514

fix #514

irc/channel.go

 		return targetMode != modes.ChannelFounder && targetMode != modes.ChannelAdmin
 	case modes.Halfop:
 		// halfops cannot kick other halfops
-		return targetMode != modes.ChannelFounder && targetMode != modes.ChannelAdmin && targetMode != modes.Halfop
+		return targetMode == modes.Voice || targetMode == modes.Mode(0)
 	default:
 		// voice and unprivileged cannot kick anyone
 		return false

irc/modes.go

 		hasPrivs = true
 	} else if channelUserModeHasPrivsOver(clientMode, targetModeNow) && channelUserModeHasPrivsOver(clientMode, targetModeAfter) {
 		hasPrivs = true
+	} else if change.Op == modes.Remove && account == change.Arg {
+		// you can always de-op yourself
+		hasPrivs = true
 	}
 	if !hasPrivs {
 		return nil, errInsufficientPrivs