Add autocompletion to Page Forms spreadsheet-style display

The Page Forms extension provides a spreadsheet-style editing display in two places-

1. In the page Special Pages: MultiPageEdit - Using this user can edit multiple pages that are using a particular template in a spreadsheet-style display which makes it easier to modify the pages or add new pages.
2. In regular forms, with the form definition setting "display=spreadsheet"- Using this user can edit the values of different fields of multiple instances of the template within the same page in a spreadsheet-style display.

Currently, the spreadsheet-style display uses the jExcel JavaScript library, jExcel provides a number of input types (dropdowns, dates, etc.) but it does not by default allow for autocompletion using an arbitrary list of values. So, this project will allow autocompletion using "values from external data" and "value dependent on"(autocompletion where one field's value depends on what was chosen for previous fields). This auto-completion will support all the pages that match a specific category, Cargo field, SMW property, or SMW concept. This autocompletion will be implemented with WikiMedia's OOUI which will help in maintaining consistency across all other extensions too.