WIP: add electrum server

[kcalvinalvin]

Change Description

Adds an electrum server to btcd. Still WIP. Lots of things to do.

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[gosunuts]

Cool! Is it part of the btcd daemon, or does it run separately?

[kcalvinalvin]

Cool! Is it part of the btcd daemon, or does it run separately?

It's a part of the btcd daemon. btcd will start listening on ports 50001 and 50002 when the electrum server is enabled.