Store pending messages in list.
Store pending messages in list.

This avoids copying elements around as they are added to the back and fetched from the front.

theurere/spreed-webrtc,tymiles003/spreed-webrtc,theurere/spreed-webrtc,cfrisemo/spreed-speakfreely,tymiles003/spreed-webrtc,theurere/spreed-webrtc,gerzhan/spreed-webrtc,cfrisemo/spreed-speakfreely,cfrisemo/spreed-speakfreely,strukturag/spreed-webrtc,tymiles003/spreed-webrtc,fancycode/spreed-webrtc,shelsonjava/spreed-webrtc,gerzhan/spreed-webrtc,tymiles003/spreed-webrtc,shelsonjava/spreed-webrtc,tymiles003/spreed-webrtc,gerzhan/spreed-webrtc,strukturag/spreed-webrtc,theurere/spreed-webrtc,theurere/spreed-webrtc,gerzhan/spreed-webrtc,strukturag/spreed-webrtc,gerzhan/spreed-webrtc,fancycode/spreed-webrtc,fancycode/spreed-webrtc,shelsonjava/spreed-webrtc,shelsonjava/spreed-webrtc,cfrisemo/spreed-speakfreely,fancycode/spreed-webrtc,gerzhan/spreed-webrtc,fancycode/spreed-webrtc,gerzhan/spreed-webrtc,shelsonjava/spreed-webrtc,shelsonjava/spreed-webrtc,theurere/spreed-webrtc,strukturag/spreed-webrtc,fancycode/spreed-webrtc,strukturag/spreed-webrtc,strukturag/spreed-webrtc,cfrisemo/spreed-speakfreely,shelsonjava/spreed-webrtc