* helm.el (helm-marked-candidates): Handle wildcard when files key is specified.
* helm-files.el: Use it in most all helm-marked-candidates calls.
* helm-grep.el (helm-grep-prepare-candidates): Simplify handling of wildcard.
* helm-mode.el (helm-read-file-name): Handle wildcards here too.
* helm-grep.el: add comments. no change.
* helm-mode.el (helm--completion-in-region): predicate is unused and should not be in the all-completions call.
It is only related to the mode in charge of displaying the ugly *Completions* buffer,
but never used by helm.