Session extension (#459)

Session extension bindings

src/error.rs

@@ -290,3 +290,12 @@ pub fn error_from_handle(db: *mut ffi::sqlite3, code: c_int) -> Error {
     };
     error_from_sqlite_code(code, message)
 }
+
+macro_rules! check {
+    ($funcall:expr) => {{
+        let rc = $funcall;
+        if rc != crate::ffi::SQLITE_OK {
+            Err(crate::error::error_from_sqlite_code(rc, None))?;
+        }
+    }};
+}