Remove "delayed conref domain" from DITA 2.0

[robander]

Proposal to remove "delayed conref domain" from DITA 2.0. The domain added three elements in DITA 1.2. Based on informal polling, it does not appear to be used, and many do not know what the three elements are for. Suggest removing from DITA 2.0 as part of effort to simplify the language and remove features that are not needed.

Discussed at TC Sept 5 2017 and assigned as stage 1 to Alan Houser.

Based on email thread begun by Kris:
https://lists.oasis-open.org/archives/dita/201708/msg00056.html

Moved to stage 2 at TC Sept 19 2017 with Alan Houser as owner.

Discussed Jan 9 2018: aiming to complete Stage 2 proposal by Jan 29

06 Feb 2018: Stan Doherty assigned as reviewer.

Voted Feb 20 to move from Stage 2 to Stage 3.

[ahouser]

Stage 2 proposal available for TC review at https://www.oasis-open.org/apps/org/workgroup/dita/download.php/62461/delayed_conref.html

[ahouser]

I've revised the stage 2 proposal based on comments by @robander (thanks!). Revision for TC review is at https://www.oasis-open.org/apps/org/workgroup/dita/download.php/62481/latest/delayed_conref_revised.html

[keberlein]

Kris and Robert are stage three reviewers; June 12 as target date for presentation to TC

[ahouser]

Stage 3 proposal available at -- https://www.oasis-open.org/committees/document.php?document_id=63270&wg_abbrev=dita. Reviewed by Kris and Robert; changes incorporated.

[ahouser]

Revised Stage 3 proposal with updated title (replaced "Deprecate" with "Remove").
https://www.oasis-open.org/apps/org/workgroup/dita/download.php/63319

[robander]

To finish up record keeping here, the stage 3 proposal from June 18 was approved on June 26: https://lists.oasis-open.org/archives/dita/201806/msg00057.html

[robander]

Completed with #171.