Import secret keys as PubSec, WIF and EWIF format

We only import json file format for now.

Add secret key files import in PubSec ,WIF and EWIF formats.

added To Do label

removed To Do label

added To Do label

changed milestone to %0.52.x

added Doing label and removed To Do label

Done in the same time as issue #50 (closed). See commits referencing issue #50 (closed).

closed

removed Doing label

mentioned in commit 5a287fe9

mentioned in merge request !52 (merged)

mentioned in commit 8bcc1373

mentioned in issue silkaj#7 (closed)

mentioned in issue #69 (closed)

mentioned in commit silkaj@bb568d35

mentioned in commit silkaj@61a0aeef

added Crypto label

added Feature label and removed enhancement label