Add rollable tables which use die results or card draw results

Check with Zephp to see how he implemented this as an extension for 4E. A lot of the library modules for SW use auto-generation of items using die rolls or card draws and it would be nice if these could be fully automated via a built-in mechanic. This could be documented for use by other devs in new library modules and could lead to the development of custom made "generator" modules -- such as an NPC generator complete with random stat sets, edge, origins, etc.