Fix papers appearing multiple times in publications

Restrict the list of publications to the main bibliography. This
prevents own papers that are cited in other own papers from appearing
multiple times in the publication list. This would otherwise happen due
to the bibliography keys having a per-paper prefix and therefore being
treated as different papers by biblatex.

As a disadvantage, all own papers now have to be listed in main.bib and
do not show up automatically anymore in the list when they are cited in
other papers.

main.tex.php

@@ -146,7 +146,7 @@ if (isset($options["--cv"]))
 \renewcommand*\thesection{\arabic{section}}
 
 \bgroup
-\begin{refsection}
+\begin{refsection}[main]
 \chapter*{List of Publications}
 \label{sec:publicationlist}
 \addcontentsline{toc}{chapter}{List of Publications}