Add GetCaptionOrHeadword() to CmPicture

[mark-sil]

This change is to add a “Caption or Headword” field in Fieldworks
Dictionary Configuration. The feature is described in the first part
of this Jira ticket:
https://jira.sil.org/browse/LT-21648

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This change is 

[jasonleenaylor]

src/SIL.LCModel/DomainImpl/CmPicture.cs line 254 at r1 (raw file):

				{
					// Need to call this to get the actual ws.
					WritingSystemServices.GetMagicStringAlt(Cache, wsId, Hvo, Caption.Flid, true, out wsActual);

Shouldn't this be the flid for the Headword?

[jasonleenaylor]

Reviewed 3 of 4 files at r1, all commit messages.
Reviewable status: 3 of 4 files reviewed, 1 unresolved discussion (waiting on @mark-sil)

[mark-sil]

Reviewable status: 2 of 4 files reviewed, 1 unresolved discussion (waiting on @jasonleenaylor)

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src/SIL.LCModel/DomainImpl/CmPicture.cs line 254 at r1 (raw file):

Previously, jasonleenaylor (Jason Naylor) wrote…

Shouldn't this be the flid for the Headword?

Changed flid to zero and use a GetMagicStringAlt() wrapper class that more accurately describes why we were making the call.

[jasonleenaylor]

Reviewed 2 of 2 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @mark-sil)