Consistent rebin behaviour

[Nick Draper]

From Garrett:

If the Input and Output workspaces are the same during a rebin process, the workspace type remains event where if they are different, it converts to a 2D workspace.

By default it should always convert. Alternatively there should be a flag to tell it to convert or not.

From Russell:

I agree with this request - when I was sitting at the back of the Mantid demo and this behaviour was explained it struck me that it was slightly evil and I meant to bring it up.

Probably a PreserveEvents property is appropriate (though it is unfortunate that this would then show up in the algorithm gui even when it's irrelevant).

Any objections? I realise there will be scripts to fix.....

[Russell Taylor]

Add a PreserveEvents or KeepEvents property and make it true by default (in contrast to what Garrett suggested).

At the same time, rename the MatrixWorkspaceOut property on DiffractionFocussing to match this.

[Janik Zikovsky]

(In [10536]) Fixes #2624: Rebin now has a parameter to PreserveEvents, instead of relying on the name to decide what type of workspace the output should be. Also, change in DiffractionFocussing parameters: check your scripts!

[Russell Taylor]

(In [10552]) Fix SNS reducer for less-magic Rebin algorithm. Re #2624.

[Michael Whitty]

tested in 11105. I have updated the documentation for Rebin to reflect this change.

[Stuart Campbell]

This ticket has been transferred to github issue ​3471