v1.18.0

• Based on code of Synapse 2.99.2.
• Fixes build problems on vala 0.36.
• Properly construct OptionEntry.
• Set and update client-window of Gtk.IMMulticontext.
• Silence desktop-entry-lacks-keywords-entry.
• Only show in MATE Desktop.
• Disabled several plugins not everyone uses. Just enable in preferences the ones you want.