Updated to docker-asciidoctor:1.1.0 image

Updated asciidoctor and pandoc images

default sans and code font changed to source*pro

Updated templates with upstream changes

- improved listings handling in regard of fonts and style
- safeguarded \renewcommands in case the command isn't defined yet

minor updates to pandoc and asciidoctor images

- When using the gitinfo hook, the version matching pattern can now
  be specified using the environment variable GITINFO_RELTAG_MATCH.
  Default is '*' which matches any tag
- Corrected pandoc image COPY command to preserve symbolic links
- extended the asciidoctor image with similar helper tools as the
  pandoc image contains

pandoc updated to 2.6

- image based on alpine-glibc
- texlive installation done using install-tl and tlmgr

- pandoc updated to 2.
- asciidoctor updated to 1.5.8

updated underlying base image

update of pandoc to 2.2.1
update of base image

styling adjustments

added new template for hsr specific document creation

gitlab_links.py corrections and improvements

latex template updates and new book processing script

Update of pandoc(-citeproc) to 2.1.1

changed base image to archlinux

use specific ubuntu image as base, allow pandocfilters from PATH

xperimental image containing hooks