Memoization across property types

[bestchai]

The dominant use-case for Texada will probably involve multiple property types. That is, Texada will mine instances for multiple types on the same log in a single run. In this case, we can do better than just memoizing across property instances of the same type. We can also memoize and re-use results across property types.

Some of the same issues arise in this memoization process as for memoizing between property instances:

• What order to use for mining property types?
• How long to keep memoized state across property types?

[Issue created by bestchai: 2015-07-01]

[Comment created by carolemieux: 2015-07-01]
Note that this will require solving Issue 38 as well.