Why doesn’t this work?
mytext = mytext:gsub(" ", “%20”)
Or even better, how do I make it work? 
Oskwish [import]uid: 24111 topic_id: 21588 reply_id: 321588[/import]
% needs to be escaped
mytext = mytext:gsub(" ", “%%20”) [import]uid: 119459 topic_id: 21588 reply_id: 85616[/import]