Add multi match support in GID and update grep help.

* helm-help.el (helm-grep-help-message): Do it.
* helm-id-utils.el (helm-gid-candidates-process):
Provide multi match support, with highlighting not fully working.

helm-help.el

@@ -624,6 +624,9 @@ Helm Gid use the symbol at point as default-input.
 You have access to this command also from `helm-find-files' which allow you to
 navigate to another directory to consult its database.
 
+NOTE: Helm gid support multi matches but only the last pattern entered will be
+highlighted due to the lack of ~--color~ support in GID itself.
+
 * Helm AG
 
 ** Tips
@@ -636,6 +639,12 @@ This file supports same entries as what you will find in `helm-grep-ignored-file
 `helm-grep-ignored-directories'.
 As always you can access helm AG from `helm-find-files'.
 
+Starting at version 0.30 AG allow providing one or more TYPE argument on its command line.
+Helm provide completion on these TYPES arguments when available with your AG version,
+Use a prefix argument when starting helm ag session to get this completion.
+NOTE: You can mark several types to match in your ag query, however on the first versions of
+AG providing this, only one type was allowed, so in this case the last marked will take effect.
+
 ** Commands
 \\<helm-grep-map>
 \\[helm-goto-next-file]\t\tNext File.

helm-id-utils.el

@@ -39,11 +39,18 @@ MacPorts to install id-utils, it should be `gid32'."
   :type 'string)
 
 (defun helm-gid-candidates-process ()
-  (let ((proc (start-process
-               "gid" nil helm-gid-program
-               "-r" helm-pattern)))
-    (set (make-local-variable 'helm-grep-last-cmd-line)
-         (format "%s -r %s" helm-gid-program helm-pattern))
+  (let* ((patterns (split-string helm-pattern))
+         (default-com (format "%s -r %s" helm-gid-program
+                              (shell-quote-argument (car patterns))))
+         (cmd (helm-aif (cdr patterns)
+                  (concat default-com
+                          (cl-loop for p in it
+                                   concat (format " | grep --color=always %s"
+                                                  (shell-quote-argument p))))
+                default-com))
+         (proc (start-process-shell-command
+                "gid" helm-buffer cmd)))
+    (set (make-local-variable 'helm-grep-last-cmd-line) cmd)
     (prog1 proc
       (set-process-sentinel
        proc (lambda (_process event)