Include function to get cfitsio version

Note: currently only works on cfitsio >= v4.0.0 since versions previous
to this don't include the `CFITSIO_MICRO` symbol used in this function.

TODO: update this

fitsio-sys/examples/print_version.rs

@@ -0,0 +1,5 @@
+use fitsio_sys::cfitsio_version;
+
+fn main() {
+    println!("cfitsio version: {}", cfitsio_version());
+}

fitsio-sys/src/lib.rs

@@ -98,3 +98,29 @@ mod sys {
 }
 
 pub use sys::*;
+
+// global functions
+
+/// Representation of the version of cfitsio used within bindings
+pub struct CfitsioVersion {
+    /// Patch version
+    pub patch: u32,
+    /// Minor version
+    pub minor: u32,
+    /// Major version
+    pub major: u32,
+}
+
+impl std::fmt::Display for CfitsioVersion {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}.{}.{}", self.major, self.minor, self.patch)
+    }
+}
+
+pub fn cfitsio_version() -> CfitsioVersion {
+    CfitsioVersion {
+        patch: CFITSIO_MICRO,
+        minor: CFITSIO_MINOR,
+        major: CFITSIO_MAJOR,
+    }
+}

fitsio/src/lib.rs

@@ -1049,6 +1049,9 @@ let _hdu = t.hdu(hdu_num).unwrap();
 
 pub use fitsio_sys as sys;
 
+// re-export version information
+pub use sys::{cfitsio_version, CfitsioVersion};
+
 #[macro_use]
 mod macros;
 mod fitsfile;