[FEATURE] listtrustlines endpoint from account to cold wallet.
[FIX] use "state" to list failed payments

[TEST] All failed payments should have "failed" state.
Merge pull request #121 from ripple/fix-listfailed

Fix listfailed
Merge pull request #119 from ripple/trustlines

Trustlines
[CHORE] Add release notes, bump minor version.
Merge pull request #129 from ripple/release-3.21.0-rc1

Release 3.21.0 rc1