Requests for comment/Inline diffs

I propose to integrate inline (one-column) diffs from MobileFrontend into MediaWiki core. Mobile screens are smaller so standard side-by-side diffs aren't good. To address this, the mobile team developed a new diff mode. Example diff.

Implementation details
Inline diffs use existing core diff code as much as possible, therefore the code is very compact and has the same performance characteristics as two-column diffs. Just two small classes: diff formatter and a DifferenceEngine subclass - this should not create maintenance problems.

Because performance matters, Wikimedia's PHP extension wikidiff2 already supports inline diffs.

Intended goals
Primary: Whether inline diffs should be integrated into core.

Secondary: if we decide to integrate, I'd like comments on some details.
 * Current mobile designs don't show numbers of modified lines, however the diffs contain everything for core to display them, for example:   . How exactly should line numbers look like? My current idea is "Lines 123/456" and it looks ugly.
 * How to switch between diff modes? My current thought is to display old diffs by default but offer a link to inline version on diff view and remember this choice (in user prefs? via cookie?).
 * Large inline diffs can be cryptic - should MediaWiki automatically switch to side-by-side mode if the change is huge?