Update submodules: plugins (new commits)

plugins:
    b18c24b Greg Holmes <greg@dmdirc.com>
            Add ability to change aliases to new alias dialog.

            Gerrit: http://gerrit.dmdirc.com/3538

Change-Id: Idd659d3e20bafd107c64c42353bffad4fee0ddb3
Fix saving for core alias dialog model.

Change-Id: I5c4a0cabf19c4304aa6f3312eec9233ec34029fd
Reviewed-on: http://gerrit.dmdirc.com/3539
Automatic-Compile: DMDirc Build Manager
Reviewed-by: Chris Smith <chris@dmdirc.com>