If installed, prefer the `ueberdosis/pandoc` package over `ryakad/pan…

…doc-php` (#108)

* If installed, prefer the ueberdosis/pandoc package over ryakad/pandoc-php

(cherry picked from commit 5490164)

* Creation of the Pandoc converter & checking for installed packages now only happens once, and throws an exception in case requirements aren't met

(cherry picked from commit 82d8327)

* Mention the Pandoc wrapper package ueberdosis/pandoc as an alternative to ryakad/pandoc-php

(cherry picked from commit fdd7a6a)

* Add tests with alternative pandoc wrapper, fix CS, add PHP 5.6 support

Fix CS check (#104)

Merge pull request #95 from eknoes/umlauts

Allow special characters in citation keys

Fix TOC in readme

prepare release 1.0.5

Revert "commit composer.lock"

This reverts commit df0de91.

Merge branch 'bug44-v2'

prepare release 1.0.4

prepare release 2.0.0

prepare release 1.0.3