[BioC] important bug fix in the package affy

[Laurent Gautier]

To whom it makes concerned:

The released version of the package problem suffered from a rather annoying
problem in the method 'computeExprSet'. As a result, the expression values
computed have very good chances to be rather incorrect (whatever the method
you used). Many thanks to Michael Morley for warning us about strange results
compared to MAS5.0 (the bug was found while digging that).
I would strongly recommend to re-run expression value computation with
the version 1.1.1 of the package (should appear by tomotrrow on the website)
if you are currently working with expression data obtained with 1.1.

Sorry for the inconvenience. 



Laurent