Merge branch 'dubp/mnemonic-hd-only' into 'master'

Cargo.lock

lib/models/generateWallets.dart

native/dubp_rs/Cargo.toml

native/dubp_rs/src/dewif.rs

native/dubp_rs/src/dewif/bip32.rs

native/dubp_rs/src/error.rs

native/dubp_rs/src/lib.rs

native/dubp_rs/src/secret_code.rs

packages/dubp_rs/README.md

packages/dubp_rs/lib/dubp.dart