Per board configuration names were not working

When I moved a thread, the default name "Anonymous" was used even though I set "Anonymage" in config.php for the board.

![2013-03-20-075740_916x543_scrot](https://f.cloud.github.com/assets/838783/280393/83f8fba8-9155-11e2-89e4-cd8c36218df3.png)

This is because the `shadow_name` configuration option inherits from the default "Anonymous" in config.php.

This commit fixes that.

![2013-03-20-075928_910x286_scrot](https://f.cloud.github.com/assets/838783/280394/96d01d88-9155-11e2-821b-47ef0f60c3fa.png)