* helm-source.el: Handle match plugin from classes.
(helm-source): remove no-matchplugin and add matchplugin.
(helm-source-mp-get-search-or-match-fns): Setup mp fns.
(helm-source-in-buffer): Remove candidates-in-buffer and dont plug match
plugin.
(helm-source-sync): dont plug match plugin.
* helm-source.el (helm-source-mp-get-search-or-match-fns): Use let.