New DocBook support (0003)

[Pavel Sanda]

On Fri, Jun 26, 2020 at 06:56:04PM +0200, Thibaut Cuvelier wrote:
> (This is a follow-up to https://www.lyx.org/trac/ticket/8444, cleanly
> divided in several patches and reviewed by Guillaume.)

Patch 0003 will break packaging, because the file is deleted without removing
it's corresponding part in Makefile.am (it's generally good idea to do git grep
to check for leftovers).
Secondly I see similarly named file in templates. Is this supposed to stay?

Pavel