Added source and preconfigured function for Wikipedia lookup with Wikipedia suggestions.
* helm.el (helm-update): (#463) Compute candidates in own loop, use helm--maybe-use-while-no-input. * helm-files.el (helm-source-find-files): No need now to delay. * helm-mode.el: same.
* helm.el (helm-update): Fix comments, the not flickering feature is now disabled.
* helm.el (helm-update): Add more comments.
* helm-files.el (helm-dired-action): Fix following.
Merge pull request #461 from nerton/wikipedia_lookup

Added Wikipedia lookup with suggestions from Wikipedia
* helm.el (helm--compute-sources): New.
(helm-process-delayed-sources, helm-update): use it.
* helm-net.el: Fix and simplify wikipedia suggestions.
* helm-net.el: declare json-read-from-string.
* helm-net.el (helm-wikipedia-parse-buffer): New.
(helm-wikipedia-suggest-fetch): Use it allow using curl to fetch data.
* helm-help.el: Document `helm-find-files' behavior (#464).
* helm-help.el (helm-read-file-name-help-message): Use a part of helm-find-files doc.
* helm-config.el: Use now helm-filtered-bookmarks by default.
* helm-net.el (helm-wikipedia-suggest-fetch): Remove second arg of url-retrieve-synchronously for compatibility.
Additional actions on helm-etags items and keybindings

This commit generalizes the `helm-etags-default-action' to accept a
function that is used on the filename.

This allows the addition of actions like find in other window/frame.
It also adds `C-c o` to open tag in other window and `C-c C-o` to open
tag in other frame.
Merge pull request #465 from markus1189/helm-etags-other

Additional actions on helm-etags items and keybindings
* helm-buffers.el (helm-buffers-persistent-kill): Fix preselection.
Added persistent action to wikipedia suggest which shows the summary of a topic.
Merge pull request #467 from nerton/wikipedia_persistent

Added persistent action to wikipedia suggest which shows the summary of a topic
* helm-net.el: Minor changes to last wikipedia feature (use "when" when possible which is more readable)