* helm-files.el: Allow removing files from file-cache.
(helm-ff-file-cache-remove-file
helm-transform-file-cache): new.

* helm-source.el (helm--setup-source): Add transformer for file-cache
to type file.
* helm-files.el: Allow removing marked files in file-cache.
(helm-ff-file-cache-remove-file-1): new.
(helm-ff-file-cache-remove-file): delete on marked.
* helm-files.el (helm-transform-file-cache): Change title of action.