Set Thunderbird to use Gmail’s Trash folder

Sorting all my mail the other day, I realised that Gmail still keeps a copy of every email in the “All Mail” folder. Only if the messages are moved to Gmail’s “Trash” folder, they are eventually deleted. This cannot be set in Thunderbird directly afaik. Here is what you have to do.

sed one-liners

Handy one-liners for UNIX stream editor sed.