Allow building selected packages with --package

Issue #22

src/main.rs

@@ -82,7 +82,7 @@ enum OuterCommand {
 #[clap(version, about)]
 struct Args {
     /// Directory containing crate to analyze. Defaults to current working directory.
-    #[clap(short, long)]
+    #[clap(long)]
     path: Option<PathBuf>,
 
     /// Path to cackle.toml. Defaults to cackle.toml in the directory containing Cargo.toml.
@@ -163,6 +163,12 @@ struct Args {
     #[clap(long)]
     no_backtrace: bool,
 
+    // We may at some point allow this to be a short flag, but should probably wait a few releases.
+    // -p was previously accepted for --path.
+    /// Packages to build and analyse.
+    #[clap(long)]
+    package: Vec<String>,
+
     #[command(subcommand)]
     command: Option<Command>,
 }

src/proxy.rs

@@ -121,6 +121,9 @@ impl<'a> CargoRunner<'a> {
             self.args,
             &self.config.raw.common,
         );
+        for pkg in &self.args.package {
+            command.arg("-p").arg(pkg);
+        }
         if self.args.command.is_none() {
             let default_build_flags = ["--all-targets".to_owned()];
             for flag in self