R1:b33e373503c6

Drag & Drop: set a link as external

Summary:
Rest assured: external links remain evil, by default.

Don't adopt them randomly by induction.

Whether you believe it or not, this specific external
link merited some deep thoughts on Phorge:

- https://we.phorge.it/T15172

So, whenever you use a mouse, a finger, or whenever we have
a confirmation dialog or not to prevent onblur disasters,
this change is probably consistent with common expectations.

Having said, external links remain evil - by default.