Requests for comment/UploadWizard: scale to sister projects

This request for comment is about UploadWizard software which the Multimedia Team (WMF) is about to embrace and take over starting within next weeks and processing it during 2014, per the text on the software page.

Proposed change
What I would like to propose is to restructure the UploadWizard software to make the following functionality available to contributors:
 * Edit text of each wizard screen on-wiki.
 * Edit the flow of the wizard (which buttons exist on a screen, where they take) on-wiki.

Context
This request is based on the following observations:
 * English and Russian Wikipedia's article creation wizards appear to be entirely markup-based, with no JS. Contributors have the flexibilities mentioned above, but lack some nice flexible things JS would let them do, such as choosing a next wizard screen depending on multiple previous choices, or entering partial data to be carried forward from page to page.
 * A product which has the flexibilities mentioned above would have the potential to be deployed across all sister projects.
 * Such a product would also have the potential to work a bit gadget-like, to address use-cases I call “interactive templates”, to aid in daily editing routine and make it more intuitive.
 * A JS-based product of this kind is under development on English Wikinews.
 * Multimedia Team mention they would start working “in the coming weeks”, making feedback pertinent earlier better than later.
 * Editing on-wiki is more collaborative than querying editing files (like ones in an Extension) would be.
 * Markup should also be less-prone to security risks.

Discussion
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