[dev-context] bib: space gobbled after \cite

[Sanjoy Mahajan]

With recent versions of ConTeXt, spaces after \cite[Author:1977] are
getting eaten.  I'm pretty sure that did not happen with versions from a
while ago, but the archives suggest that it happened a long while ago:

   <http://www.mail-archive.com/ntg-context@let.uu.nl/msg00062.html>

The minimal test file:

=============================================
\usemodule[bib]
\setupbibtex[database=statement, sort=author]

\starttext

Polya said \cite[Polya:1966] in 1966: "finished mathematics consists
of proofs, but mathematics in the making consists of guesses."

\blank
\placepublications

\stoptext
==============================================

The first line ends up "Polya said (Polya, 1966)in 1966..." with no
space after the close paren.  (This is with 2009.10.27 16:35 MKII on top
of TL 2009 from Debian.)

Here is statement.bib to complete the example:

@Misc{Polya:1966,
  author =	 {George Polya},
  title =	 {Let us teach guessing},
  howpublished = {VHS},
  year =	 {1966},
  publisher =	 {Mathematical Association of America},
}

-Sanjoy

`Until lions have their historians, tales of the hunt shall always
 glorify the hunters.'  --African Proverb