Merge Maturity in Candid

[lmuntaner]

Even though "Merge Maturity" is deprecated and we changed the proto implementation to show "Stake Maturity" we would like also implement the transaction in candid for backwards compatibility.

Here are the test vectors:

merge-maturity.json.txt

Functionality should be the same as "Merge Maturity" in proto that shows "Stake Maturity" in the screen.

Thanks!

:link: zboto Link

[lmuntaner]

Deprecated transaction