Add a way to enter a bitcoin URI in GUI #3202

Add a way to enter a bitcoin URI manually in the GUI or to open a payment request manually from a file.

I think this can be useful in some cases, for example to quickly enter a URI if bindings have not been set up properly, and for testing programs that generate bitcoin URIs / payment requests, and so on.

User interface wise this could be done in (at least) two ways:

• Add a "Open URI" under File menu, analogous to Torrent clients
• or make it possible to enter URIs directly into Pay to: in the Send tab (but this feels a bit like a hack)

Anyone agree? @diapolo?

Yeah, good idea and also fine if we are able to use payment requests via files (AFAIK the code is already nearly in the client).

It is already possible to drop an URI into the GUI, but this doen't work for payment request URLs yet.

I've got a nice little patch in the work, which allows drag and drop of payment request URIs :).