Initial release, version 1.2.0

wikEdDiff: inline-style difference engine with block move support.

Requires a patch to core, see README.text.

WikEdDiff.php and the JavaScript library wikEd diff are synced one-to-one ports. Changes and
fixes are to be applied to both versions.

JavaScript library (mirror): https://en.wikipedia.org/wiki/User:Cacycle/diff
MediaWiki extension: https://www.mediawiki.org/wiki/Extension:wikEdDiff
JavaScript online tool: http://cacycle.altervista.org/wikEd-diff-tool.html

Features:

- Visual inline style, changes are shown in a single output text
- Block move detection and highlighting
- Resolution down to characters level
- Unicode and multilingual support
- Stepwise split (paragraphs, sentences, words, characters)
- Recursive diff
- Optimized code for resolving unmatched sequences
- Minimization of length of moved blocks
- Alignment of ambiguous unmatched sequences to next line break or word border
- Clipping of unchanged irrelevant parts from the output (optional)
- Fully customizable
- Text split optimized for MediaWiki source texts
- Well commented and documented code

Change-Id: Ide8677179e73080c8084803be1ebf09f6f582809