ADD ability to determine if channel is railed

[andrewjaykeller]

Would be nice if we could query a channel number and see if it is railed like

for ( i = 0; i < board.numberOfChannels(); i++) {
    var railed = board.isRailedChannel(i + 1);
    if (railed) console.log("Channel " + (i+1) " railed");
}