Updated mediawiki/extensions
Project: mediawiki/extensions/ExternalData  8187952c13d63872806465e6f91c4d255d7557b4

Fix for param parsing changes from r3bd2ec0

Previous parsing, in place since Nov. 2012, couldn't successfully parse
"local variables" with an underline, e.g. "a_b=c".

Change-Id: I6c6414610fddfe80898c8fe1e2b4278c38b386fd