expand et:// protocol
This is a feature request from iliwieckz:
Unvanquished has 3 ways of handling the unv:// protocol:
unvanquished +connect gg.illwieckz.net:27960 unvanquished +connect unv://gg.illwieckz.net:27960 unvanquished unv://gg.illwieckz.net:27960
The first two are already implemented. The third way is useful for the Linux static version, as the et:// protocol is normally handled through packaging which isn’t done for static Linux. Having the third option allows to easily click on an et:// link through the browser, and simply choose the "etl" application as default app to open these links.