Update release notes

    See also
    git log --format=oneline 5aaed4416f14cff5a27b475a73a9681911f8a70b..HEAD

    For a full list since the last release, see (for 1.9 / 1.9.1):
    git log --format=oneline 269e3f56256fe650d90233b8b34e667c49dda3b3..HEAD
    git log --format=oneline ec7f68a2e264931cf129ec8771d2b69372dc2bfd..HEAD

RELEASE_NOTES.md

@@ -5,6 +5,10 @@ Release Notes v1.10 (work in progress)
 Changes
 -------
 
+- Add API function for HTTP digest authentication
+- Improved interface documentation
+- Support parameters for Lua background scripts
+- Use new connection queue implementation (previously ALTERNATIVE\_QUEUE) as default
 - Add USE\_SERVER\_STATS define, so the server collects statistics data
 - Convert system\_info text output and all other diagnostic strings to JSON format
 - Add experimental function to query the connection status (may be dropped again)