Fix highligthting matches in *-locate-library and *-recentf (#145).

* helm-elisp.el: Redefine the source for *-locate-library using
filter-one-by-one, there is a race condition whith filtered-candidate-transformer
in those cases.

* helm-files.el: Same for recentf.
Redefine source for semantic and imenu, fix setting of fuzzy for both (#145).

* helm-imenu.el (helm-imenu-source): new class.
(helm-imenu-fuzzy-match): use a set function and move it below.
(helm-imenu): Set the source here (should be set by the fuzzy var,
but be sure it is done).

* helm-semantic.el: Same.