Gadgets/autocomplete

Summary: A context aware autocomplete that suggest links when user typing [[, and template when user type {{. The gadget takes advantage of TemplateData, and can also help to fill parameters names.

More general info about Gadgets

Setup

To setup the gadget in new project:

Add the source code
- To turn it as a gadget that user can select in their preferences (requires sysop rights):
  1. create MediaWiki:Gadget-autocomplete.js with the following code:
```
mw.loader.load('//he.wikipedia.org/w/load.php?modules=ext.gadget.autocomplete');
```
  2. create MediaWiki:Gadget-autocomplete with short description
  3. add it to MediaWiki:Gadgets-definition
- To test it (if you aren't sysop):
  1. add the source code to your personal JS (Special:MyPage/common.js).
```
mw.loader.load('//he.wikipedia.org/w/load.php?modules=ext.gadget.autocomplete');
```

The gadget use the same mechanism as the suggestion in the searchbox, only pages that appear in the search will be suggested.
The gadget suggest links when user start to type [[ and typed at least the beginning of the pagename.
The gadget suggest links also when a template parameter is filled is expecting page name based on template data (see #Templatedata)
The gadget supports links to sections (such as Wikipedia:Featured articles#Biology when user type [[Wikipedia:Featured articles#). By design this is supported only when editing pages not in main space.

Similarly to links, the gadget suggest template names when user start to type {{

The gadget complete parameter names when user is within a template and typed | if the template has templatedata.
For templates expecting unnamed parameters, the gadget expect the user to first fill the unnamed parameters and doesn't suggest parameter name. For example
- Template source: the user page is [[User:{{{1|{{{Username}}}}}}]]
- when user typed {{template|User<span style=" it isn't possible to know whether the user typed a name of a user starting with "User" or started to type the parameter name "Username". The gadget assume the first option.
- For parameters indicated as referring to other pages, the gadget suggest filling similar to links and templates. Supported parameters types:
- wiki-page-name
- wiki-file-name
- wiki-user-name