Merge #124: Migrate from structopt to clap.

b20a140 Fix some clippies.. (rajarshimaitra)
1e21cc7 Fix wasm (rajarshimaitra)
ba1c165 Update cargo lock. (rajarshimaitra)
02e71b0 Reverse the recipient parsing string (rajarshimaitra)
95719b0 Remove vector of string from compact_filters options. (rajarshimaitra)
9fb651a Update wasm build to 1.57 in CI (rajarshimaitra)
7e87a65 update MSRV to 1.57 (rajarshimaitra)
3dcc269 Update Cargo lock (rajarshimaitra)
f8c0f2e Update recipient parsing in handlers. (rajarshimaitra)
5bbc45a Move from structopt to clap (rajarshimaitra)

Pull request description:

  <!-- You can erase any parts of this template not applicable to your Pull Request. -->

  ### Description

  Fixes #113.

  This is an attempt to migrate from `structopt` to `clap v0.3` which provides very similar kind of derives as `structopt`. Changes are straight forward. But this comes with few more problems.

   - with clap `v3.2.22` the MSRV pushes up to `1.57.0`.. The last clap of MSRV `1.56.0` was `clap 3.2.5`.. But even that doesn't seem to be working at MSRV `1.56.0` anymore, as bunch of underlying lib has upgraded.

   - `clap v3.0` doesn't seem to support custom vector parsing well, reported here clap-rs/clap#1704. This is required for `recipient` parsing which is a `Vec<(Script, u32)>`.  Workaround for that is to use vecs of strings and parse them at runtime in `create_tx` handler. Included in the PR.

  ### Notes to the reviewers

  `structopt` is currently freezed at `clap 2.0` and doesn't seem to intend on updating and currently its has unmaintained vulnerability. And `clap v3.0` onward seems to replacing everything that `structopt` did before.  So this means we should also look for ways to migrate from `strcutopt` to `clap`.. But `clap` seemed to have moved ahead than our MSRV `1.56.0`.. So we need to take up a call on that.. Opened this PR to facilitate that discussion..

  This is draft until we figure what to do..

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk-cli/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

ACKs for top commit:
  notmandatory:
    ACK b20a140

Tree-SHA512: de3511c1531185064e3c328f0c966c3e87294b7c6d07a89ba9f64e49f7c8b8ccaef0915f49fc6721b738f91a0128b30eeb61147a2da174ccac9abab094ab6798

.github/workflows/cont_integration.yml

@@ -11,7 +11,7 @@ jobs:
       matrix:
         rust:
           - 1.60.0 # STABLE
-          - 1.56.0 # MSRV
+          - 1.57.0 # MSRV
         features:
           - default
           - electrum,sqlite-db
@@ -80,7 +80,7 @@ jobs:
       - run: sudo apt-get update || exit 1
       - run: sudo apt-get install -y libclang-common-10-dev clang-10 libc6-dev-i386 || exit 1
       - name: Set default toolchain
-        run: rustup default 1.56.1 # MSRV
+        run: rustup default 1.57.0 # MSRV
       - name: Set profile
         run: rustup set profile minimal
       - name: Add target wasm32

Cargo.toml

@@ -14,7 +14,7 @@ license = "MIT"
 [dependencies]
 bdk = { version = "0.24", default-features = false, features = ["all-keys"] }
 bdk-macros = "0.6"
-structopt = "0.3"
+clap = { version = "3.2.22", features = ["derive"] }
 serde_json = "1.0"
 log = "0.4"
 zeroize = "<1.4.0"