disk, memory caching - store objects by arbitrary key

Store any matlab objects to disk or keep them in memory, indexed by arbirary objects.

disk_cache.m
memory_cache.m

If you have a large structure, like
ds.bigArray = rand(10000)
ds.axesNames = { 'a' 'b' 'c' };

You can store it permanently to disk:
cacheId = { 'bigArray', 'version', 1 };
disk_cache('set', ds, cacheId);

It can later be retrieved by
ds = disk_cache('get', cacheId);

Advantages over using .mat files:
* indexing with arbitrary keys
* automatic detection of outdated data using outdatedKey option
* stored in one central location

Similar things can be done in-memory using memory_cache.m
Advantages over persistent variables:
* every time your m-file is changed, the memory cache is not cleared.