Requests for comment/Decorify into extensions

Rationale
The core is well on it's way to becoming bloatware. Hacks are being used in many places to support edge features and this complicates maintenance and testability of basic features. Features are being added or retained to cater only to wmp when they should be deployed via extensions.

Proposed philosophy
KISS. The core should only contain the minimum amount of functionality to operate effectively as a wiki.
 * Page creation
 * Page editing
 * Page revisions

Instead of going "kitchen sink" and trying to coreify include every single function possible (MS-WORD), extra functionality and reports should be delivered through extensions. The default mediawiki distribution/install then would include many "should have" extensions, some turned on by default and others default off. The installer would allow an administrator to tweak their install.

This would also mean we would stop supporting two different kind of systems for features (see Special Pages) -- there would be one way to do things and that system would be as robust as possible.

Candidates for extensionification

 * Revision Comparison (alternative)
 * User management (better integration of alternatives LDAP)
 * SpecialPages: almost all of Special:SpecialPages

Recognition for extension community
Our current process and attitude towards the extension community is counter-productive and harmful to the development of mediawiki. By creating the maximum possible opportunity for alternatives, our community will produce ways of managing, displaying and handling tasks that we would otherwise not have imagined.

Currently once a feature becomes ubiquitous (through an extension) or desired, someone takes upon the task of creating it a-new in the core using a different process than extensions. We abandon and fail to recognize the work of the extension authors, make their work sometimes over years obsolete and in general discourage people to try and fill obvious gaps in our software using extensions. See bug 30636 (pay special attention to how they treat the extension author and their code). There should be no reason why we can't recognize an author's work and approach them for inclusion into the distribution package, tidying it up in the process (or using a subset), this is very different than our current coreification process.