Start preparing for Lutok 0.5 release

- Bump the configure.ac version to 0.5.
- Start adding a 0.5 section to NEWS.md.

Signed-off-by: Enji Cooper <ngie@FreeBSD.org>

NEWS.md

@@ -1,5 +1,17 @@
 # Major changes between releases
 
+## Changes in version 0.5 (UNRELEASED)
+
+Released on 2024/05/XX.
+
+* Use more modern autotools macros.  Bump the minimum autoconf version to 2.68 to
+  support this change.
+
+* Modify build code to improve Lua 5.4 support.
+
+* Replace `std::auto_ptr` use with `std::unique_ptr` use.  This improves C++
+  standard support and fixes the build with newer C++ standards.
+
 ## Changes in version 0.4
 
 Released on 2013/12/07.

configure.ac

@@ -26,7 +26,7 @@ dnl THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 dnl (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 dnl OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-AC_INIT([Lutok], [0.4],
+AC_INIT([Lutok], [0.5],
         [testing@FreeBSD.org], [lutok],
         [https://github.com/freebsd/lutok/])
 AC_PREREQ([2.68])