Reduce dependencies feeding into Algorithm base class

[mantid-builder]

This issue was originally TRAC 4120

Original Reporter: Russell Taylor

There are a lot of headers which, if modified, lead to every single algorithm having to be recompiled. This can take a long time! (E.g. on a Mac mini you're looking at something approaching 2 hours).

My sense is that we can reduce this by making more use of forward declarations (thanks to our heavy use of shared pointers).

Originally, we deliberately included more than we needed to in the Algorithm and (Matrix)Workspace base classes. This is so that algorithm writers (who may be users, but in the end rarely/never are) did not need to worry about what includes to use. My feeling is that the drawbacks of this are now greater than the benefits. I will accept that there are arguments for not being as aggressive as may be technically possible.

[mantid-builder]

Russell Taylor (2011-11-14T22:27:21):
Replace IPeaks header inclusion with forward declaration.

Here's a starter on this one. Re http://trac.mantidproject.org/mantid/ticket/4120.
c5609dd

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@NickDraper (2012-01-09T09:45:09):
Moved to iteration 33 at iteration 32 code freeze

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Russell Taylor (2012-03-02T18:33:51):
Replace header inclusion with forward declaration. Re http://trac.mantidproject.org/mantid/ticket/4120.
419a9f0

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Russell Taylor (2012-03-02T19:37:32):
Remove IPeaksWorkspace & ITableWorkspace from inclusion everywhere.

Specifically from inclusion in WorkspaceFactory.h. Re http://trac.mantidproject.org/mantid/ticket/4120.
Sorry for another long build but pain now = much less pain in future.
c60808a

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Russell Taylor (2012-03-06T20:31:14):
Replace header inclusion with forward declaration. Re http://trac.mantidproject.org/mantid/ticket/4120.
419a9f0

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Russell Taylor (2012-03-06T20:31:16):
Remove IPeaksWorkspace & ITableWorkspace from inclusion everywhere.

Specifically from inclusion in WorkspaceFactory.h. Re http://trac.mantidproject.org/mantid/ticket/4120.
Sorry for another long build but pain now = much less pain in future.
c60808a

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@NickDraper (2012-04-30T14:16:06):
Moved at end of release 2.1

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@NickDraper (2012-08-10T12:45:19):
http://www.mantidproject.org/Release_Notes_2_2_Full_List

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@NickDraper (2012-10-28T11:42:50):
Moved to release 2.4

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@NickDraper (2013-01-28T09:25:17):
Moved at the code freeze for release 2.4

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@NickDraper (2013-04-29T09:50:12):
Moved to r2.6 at the end of r2.5

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@NickDraper (2013-07-26T13:59:12):
Moved to the Backlog after the code freeze for R2.6

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@NickDraper (2014-02-14T11:07:59):
bulk move to assigned at the into of the triage step

[NickDraper]

dupe of #15246