replace all cl symbol by their cl-lib equivalent.
Finish replacing cl symbols and requiring cl-lib, no compile error.
Add lexical-binding in only these 3 files, fix _source errors.
* helm.el: Fix expansion of source.
* helm-regexp.el: Fix helm-attrset source arg.
* helm-adaptative.el: Fix _source arg.
Handle most errors except condition-case err warnings, it seems working.
reindent.
Merge branch 'master' into lex
Merge branch 'master' into lex

Conflicts:
	helm-dabbrev.el
	helm-eshell.el
	helm-files.el
	helm-net.el
	helm-plugin.el
	helm-tags.el
	helm-utils.el
	helm.el
Merge branch 'master' into lex

Conflicts:
	helm-mode.el
	helm.el
* helm-mode.el: finish merging.
* helm-utils.el (helm-position): Transform in macro.
Merge branch 'origin-exp' into lex

Conflicts:
	helm-buffers.el
	helm-mode.el
	helm-utils.el
* helm.el: Fix cl-block, cl-return-from
* helm-elisp.el (helm-lisp-completion-transformer): Use typecase.
(helm-lisp-completion-at-point): Ignore errors for completion on let--bounded vars.
* helm.el: Shutup byte compiler about err args of condition-case.
Merge branch 'origin-exp' into lex

Conflicts:
	helm-elisp.el
Fix previous merge.
Update autoloads, lexical bind elisp and match-plugin.
* helm-dabbrev.el (helm-dabbrev--get-candidates): Simplify, avoid using declare.
(helm-dabbrev): Fix iterator when length of candidates is < to max len.