Split crate into shared logic library and binary crate (#52)

build.rs

@@ -1,17 +0,0 @@
-use vergen_gitcl::{Emitter, GitclBuilder};
-
-fn main() {
-    let gitcl = GitclBuilder::default()
-        .branch(true)
-        .sha(true)
-        .build()
-        .unwrap();
-    Emitter::default()
-        .add_instructions(&gitcl)
-        .unwrap()
-        .emit()
-        .unwrap();
-
-    #[cfg(target_os = "linux")]
-    println!("cargo:rustc-link-arg=-Wl,-rpath,$ORIGIN");
-}