SciYAG's backends TODO
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- Priority: High	Status: Planning	Created: 2007\11\12 23-27-46
Add a real caching mechanism to Backend. Ideally, any child of Backend could cache some data using a key (likely to be the datafile), and query for its presence/relevance.

To find out about its relevance, several possibilities:
* if a file was specified (in a way to see later), invalidate the cache
* when an item is stored in the cache, the backend should also save its state (save_state_raw).
- Priority: High	Status: Planning	Created: 2007\09\21 22-38-46
Create 3D backends !!! This is probably what is missing the most for ctioga now. 3D backends would allow many fancy things that are currently not possible with ctioga
- Priority: Low	Status: Planning	Created: 2007\09\21 22-37-19
Implement a trim filter, to systematically remove a given (integral) ratio of points "-""-" or rather to average over a certain number of points and store only the result.
- Priority: Normal	Status: Planning	Created: 2007\09\21 22-37-52
Implement an automatic binner to create histograms, as a backend
- Priority: Normal	Status: Planning	Created: 2007\10\16 18-02-38
The filter mechanism should be out of SciYAG::Backend, as it leaves the backend in a not reproducible state.
A separate mechanism (filter stack) should be written.
- Priority: Normal	Status: Planning	Created: 2007\10\16 18-06-21
The xy_data and xyz_data don't have any meaning. There actually is no reason to separate 2D and 3D and (why not ?) n"-"D datasets on the level of the backends. Implement a data_set function.
