update metadat for xyjax
added: @leahtrum's counter extension
added: @leahtrum's everymath extension
added:@leathrum's forloop extension
added: @dpvc's forminput extension
added: @leathrum's, @dpvc's knowl extension
fixed bad LoadComplete call in knowl extension
added: @leathrum's modifymenu extension
added: @dpvc/s preamble extension
added: @leathrum's toggles extension
Merge pull request #6 from pkra/master

integrate @leathrum's extensions