New DocBook support (0002)

[Pavel Sanda]

On Sat, Jun 27, 2020 at 01:01:44AM +0200, Thibaut Cuvelier wrote:
> > > * 0002 - you remove checkDocBook() call, yet the code of the function
> > > > remains. Is it still needed?
> > >
> > > Basically, this function should be replaced by True, so it can be safely
> > > removed.
> >
> > Ok, the patch please :)
> >
> 
> Here it is :). (Updated patch #2, not cumulative.)

This is now in.
I see in https://www.lyx.org/AdditionalSoftware that we used to require 
SGML tools for Docbook. This is no more the case and we can delete it,
correct?

Pavel