Memory management

[cdusold]

Add proper memory management so that the Cache and Buffer classes don't eat all the RAM during prolonged use.

[cdusold]

DiskDict, DiskList, and OrderedDiskDict have been added. Respectively, this provides random access with relatively low disk impact, a segmented list that stores infrequently used pages onto disk, and a random access dict where the elements are segmented linearly for faster ordered access, but higher disk impact. The need for OrderedDiskDict arose with the Prime factorization suite being developed, as the prime sieve was causing many page misses after a certain number, and the hashing scheme almost guaranteed that would continue indefinitely.

They aren't quite ready for use in the Cache and Buffer classes, as they are process bound. A manager class and process needs to be developed to take advantage of their use across threads.