Some gui improvements

There was no way of telling if an icon in the dot view represented a task or a family, without toggling the family grouping.  This change adds a little family indicator to the corner of family state icons.  It also makes the icon size configurable by the View menu.

![gcylc-family-icons](https://cloud.githubusercontent.com/assets/2362137/4006882/35912718-29b8-11e4-85a9-7d9761deaa1d.png)