In XDS.py option -B or -b does not work properly in case of twotheta swing.

```
In case of sat44 data set with 2theta of 20deg.
The beam center read in the refinement step is not correct.
Need to correct for the 2theta effect...

```

Original issue reported on code.google.com by `legrand.p` on 11 Nov 2009 at 11:27
