The following are now correctly escaped:
* Space at the start of a line
* Start-of-line characters after \r
* Magic links such as "RFC 123" with non-space whitespace
* URIs that don't use "://", such as "urn:foo"
* Double-underscore magic words
Bug: 53658
Change-Id: I824417e2937dd27cd1e69bd4e74ab7d21a978c75
This exists for some common text-processing functions that aren't
included in string (and therefore also aren't in mw.ustring), as well as
a logical place for the "unstrip" function requested in bug 45085.
Bug: 45085
Change-Id: I47356215fcc8ddeed5f901cd933a30021394bd78
