Fantastic work! This will be of great use to the Electrum community... especially for the folks who for whatever reason, don't or can't run Electrum, but need to "rescue" coins contained within Electrum seeds... and also for the people who always ask "What happens if Electrum disappears?"
I had
started something similar... but never got around to actually implementing the checksum stuff. I took the lazy option and simply ignored the checksum calculations!