Update submodules: plugins (new commits)

plugins:
    983b950 Greg Holmes <greg@dmdirc.com>
            Don't unload manager if its null.

            Gerrit: http://gerrit.dmdirc.com/3406

Change-Id: I3bbd618c32ca15919f818d4157b67d3ff7e8cdb6

modules/plugins

@@ -1 +1 @@
-Subproject commit f3c78b895b7483e09c1145323ca74cca5844643b
+Subproject commit 983b950b804641d906642d95355ec718139d710f