Preferences to turn off button images and make the battlemat compact

Addresses but does not resolve issue #528

http://jenkins.buttonweavers.com:8080/job/buttonmen-AdmiralJota/56/

This covers turning off button images and partially implements compact mode. 

In addition to reducing the footprint of the battlemat, compact mode should also affect the action/chat logs, but that would introduce conflicts with #337, so I'll handle that later.