Deprecate Language::markNoConversion, which confuses readers

Deprecate Language::markNoConversion, which confuses readers

Language::markNoConversion is used only within Parser.php and differs
from LanguageConverter::markNoConversion in that, contrary to its name
and its namesake, it only protects *things which look like URLs* from
language conversion.

This wasted several days of my time before I realized what was going on.
It's needless; just hoist the "looks like a URL" special casing inline
to the single place where that functionality is used.  (And I wonder
if the "looks like a URL" case is actually needed at all any more,
since most of those cases are probably free external links, which
go through a different code path, not bracketed external links.)

This is a clean-up to the clean-up that liangent performed in 2012
with e01adbfc0bd9f39adffc1f955ccc711e73818194.

Change-Id: I80479600f34170651732b032e8881855aa1204d8