(test3) Add case OTHER to remove compiler warning :P

```bash
Scanning dependencies of target test3
[ 66%] Building CXX object CMakeFiles/test3.dir/test3.C.o
sawyer/test3.C: In function ‘std::string color_name(Color)’:
sawyer/test3.C:12: warning: enumeration value ‘OTHER’ not handled in switch
```