Configure for importing from C/FFI

* Add `#[repr(C)]` on `HeadphoneButton` to hopefully be able to use it
  outside Rust
* Add `#[no_mangle]` to `run_key_action()`
* Export `run_key_action()` as a public function
* Build the crate as a static library

(But holy cow, a 19 MB library file?)

1 files changed, 2 insertions, 0 deletions

diff --git a/src/lib.rs b/src/lib.rs
index 7fb0b92..3127631 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -7,3 +7,5 @@ mod cocoa_bridge;
 mod parser;
 
 use parser::{HeadphoneButton, MapGroup, MapKind};
+
+pub use cocoa_bridge::run_key_action;