[LyX/master] DocBook: add support for DocBookGenerateTitle.

[Thibaut Cuvelier]

commit 16a1aa9901adc1f91671499b39565f9bccc2e644
Author: Thibaut Cuvelier <tcuvelier at lyx.org>
Date:   Thu Dec 22 04:38:36 2022 +0100

    DocBook: add support for DocBookGenerateTitle.
    
    The new parameter allows more flexibility when encoding some elements that have a poor mapping in DocBook, like theorems. The major use is to wrap the environment in a generic container, figure, which requires a title (but none is available).

 autotests/export/docbook/theorems-mathml.lyx |  148 ++++++++++++++++++++++++++
 autotests/export/docbook/theorems-mathml.xml |   85 +++++++++++++++
 lib/layouts/elsart.layout                    |   62 ++++++++---
 lib/layouts/theorems-ams-bytype.inc          |   53 +++++++---
 lib/layouts/theorems-ams-chap-bytype.inc     |   53 +++++++---
 lib/layouts/theorems-ams.inc                 |   51 +++++++---
 lib/layouts/theorems-bytype.inc              |   53 +++++++---
 lib/layouts/theorems-starred.inc             |   56 +++++++---
 lib/layouts/theorems-without-preamble.inc    |   83 +++++++++++----
 lib/layouts/theorems.inc                     |   51 +++++++---
 lib/scripts/layout2layout.py                 |    7 +-
 src/Layout.cpp                               |    6 +
 src/Layout.h                                 |    8 ++-
 src/TextClass.cpp                            |    2 +-
 src/output_docbook.cpp                       |   15 +++-
 15 files changed, 600 insertions(+), 133 deletions(-)