Add license headers

LICENSE

-Copyright (c) 2016, Hubert Figuière
+Copyright (c) 2016-2021, Hubert Figuière
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without

exempi-sys/src/lib.rs

+//
+// Copyright (c) 2016-2021, Hubert Figuière
+//
+// License: BSD-2-Clause
+// See top-level LICENSE file.
+//
+
 #[link(name = "exempi")]
 extern crate libc;
 

src/error.rs

+//
+// Copyright (c) 2016-2021, Hubert Figuière
+//
+// License: BSD-2-Clause
+// See top-level LICENSE file.
+//
+
 pub use c::XmpError;
 
 /// Error from XMP

src/lib.rs

+//
+// Copyright (c) 2016-2021, Hubert Figuière
+//
+// License: BSD-2-Clause
+// See top-level LICENSE file.
+//
+
 extern crate exempi_sys as c;
 #[macro_use]
 extern crate bitflags;

src/xmp.rs

+//
+// Copyright (c) 2016-2021, Hubert Figuière
+//
+// License: BSD-2-Clause
+// See top-level LICENSE file.
+//
+
 use libc::c_char;
 use std::ffi::CString;
 

src/xmpfile.rs

+//
+// Copyright (c) 2016-2021, Hubert Figuière
+//
+// License: BSD-2-Clause
+// See top-level LICENSE file.
+//
+
 use std::ffi::CString;
 use std::os::unix::ffi::OsStrExt;
 

src/xmpiterator.rs

+//
+// Copyright (c) 2016-2021, Hubert Figuière
+//
+// License: BSD-2-Clause
+// See top-level LICENSE file.
+//
+
 use crate::xmp::{PropFlags, Xmp};
 use crate::xmpstring::XmpString;
 use std::ffi::CString;

src/xmpstring.rs

+//
+// Copyright (c) 2016-2021, Hubert Figuière
+//
+// License: BSD-2-Clause
+// See top-level LICENSE file.
+//
+
 use std::ffi::CStr;
 use std::fmt;
 use std::str;

tests/lib.rs

+//
+// Copyright (c) 2016-2021, Hubert Figuière
+//
+// License: BSD-2-Clause
+// See top-level LICENSE file.
+//
+
 extern crate exempi2;
 extern crate exempi_sys;