I did as you suggested, chose in drop-down menu version 1.16 (which is latest stable version of mediawiki, and with which I intend to use LDAP plugin). A snapshot of version r61987 has been created (so that page says), which I downloaded. Now I'm a bit confused, whether what I downloaded is a snapshot of latest svn version of LDAP plugin, or it is a snapshot of release version of LDAP plugin (that has been tested with 1.16 version of mediawiki).
The trunk version of the LDAP plugin is essentially always the stable version. I don't branch plugins for versions of MediaWiki, instead I try to keep backwards compatibility as far back as possible.
Respectfully,
Ryan Lane