Paint sizes

[drphilmarshall]

We need each lens galaxy to carry a size with it (in arcsec) - these can be painted on at the same time as the colors. If a different catalog was used for positioning than painting, or if we were going to generate mock images from scratch, we'd need this size. Having the size in the catalog could also be useful when understanding the sim images later, too.

[drphilmarshall]

Tom Collett's lenspops code can help with this, at the same time as providing colors. I'll close this for now, and re-issue as part of the new program.