Add stellar-xdr bin (#198)

Cargo.toml

@@ -9,6 +9,12 @@ version = "0.0.8"
 edition = "2021"
 rust-version = "1.65"
 
+[[bin]]
+name = "stellar-xdr"
+path = "src/bin/stellar-xdr/main.rs"
+required-features = ["cli"]
+doctest = false
+
 [build_dependencies]
 crate-git-revision = "0.0.3"
 
@@ -18,14 +24,17 @@ serde = { version = "1.0.139", features = ["derive"], optional = true }
 serde_with = { version = "2.0.1", optional = true }
 hex = { version = "0.4.3", optional = true }
 arbitrary = {version = "1.1.3", features = ["derive"], optional = true}
+clap = { version = "4.0.26", features = ["derive"], optional = true }
+serde_json = { version = "1.0.89", optional = true }
 
 [dev_dependencies]
 serde_json = "1.0.86"
 
 [features]
-default = ["std"]
+default = ["std", "curr"]
 std = ["alloc"]
 alloc = ["dep:hex"]
+curr = []
 next = []
 
 # Features dependent on optional dependencies.
@@ -34,5 +43,9 @@ serde = ["alloc", "dep:serde", "dep:serde_with", "hex/serde"]
 arbitrary = ["std", "dep:arbitrary"]
 hex = []
 
+# Features for the CLI.
+cli = ["std", "curr", "next", "base64", "serde", "dep:clap", "dep:serde_json"]
+
 [package.metadata.docs.rs]
 all-features = true
+rustdoc-args = ["--cfg", "docs"]