Parse modulo

Add support for modulo t. in viewer.
The modulo annotation is parsed and the viewer adjusted. 

to test the PR;
 * Log in as ian-mrc
 * Open ```Synthetic>irf240.```
 * Check the main viewer, properties (right-hand side) preview. See screenshots
![mainviewer](https://f.cloud.github.com/assets/1022396/1391050/b9580b3a-3bf6-11e3-8c0c-664739094cb4.png)
![modulopreview](https://f.cloud.github.com/assets/1022396/1391054/bec64096-3bf6-11e3-9950-4548b73749f1.png)
![propertiesfrommodulo](https://f.cloud.github.com/assets/1022396/1391055/c1c93a96-3bf6-11e3-990f-15a1f5e10684.png)


Check that a "normal" image still works e.g. dv.