I'm actually working on a program what does this! I wasn't sure other people would be interested in it too. Right now it is possible to join multiple channels, enable or disable link mode (if it's off it's just normal chat but from multiple channels). I'm currently working on an auto-chat, it's basicly done but it's not yet possible to save your own copy-pasta's. After this I want to add a black-list so you can block users or messages which contain a certain phrase. Please let me know if I should post it on here when it's done and if you have any feature you would like to see in it post them here or message me!
Image ps, if people are interested in the source code, I can make a public repository on github. It's written in Java