Move solana-keygen into keygen/

sdk/src/bin/keygen.rs

@@ -0,0 +1,36 @@
+#[macro_use]
+extern crate clap;
+extern crate dirs;
+extern crate solana_sdk;
+
+use clap::{App, Arg};
+use solana_sdk::signature::gen_keypair_file;
+use std::error;
+
+fn main() -> Result<(), Box<dyn error::Error>> {
+    let matches = App::new("solana-keygen")
+        .version(crate_version!())
+        .arg(
+            Arg::with_name("outfile")
+                .short("o")
+                .long("outfile")
+                .value_name("PATH")
+                .takes_value(true)
+                .help("Path to generated file"),
+        )
+        .get_matches();
+
+    let mut path = dirs::home_dir().expect("home directory");
+    let outfile = if matches.is_present("outfile") {
+        matches.value_of("outfile").unwrap()
+    } else {
+        path.extend(&[".config", "solana", "id.json"]);
+        path.to_str().unwrap()
+    };
+
+    let serialized_keypair = gen_keypair_file(outfile.to_string())?;
+    if outfile == "-" {
+        println!("{}", serialized_keypair);
+    }
+    Ok(())
+}