Add suppot for prenote

[koppor]

biblatex supports prenote at cite:

\cite[hprenotei][hpostnotei]{hkeyi}

(Section 3.8 at the manual)

natbib also supports that:

\citep[see][]{jon90} ) [see 21]

(page 7 of the manual)

The standard LaTeX command does not. See https://en.wikibooks.org/wiki/LaTeX/Bibliography_Management.

Two possible ways to solve this issue

• [ ] integrate biblatex - see https://github.com/latextemplates/LNCS/issues/3
• [x] integrate natbib

[koppor]

Fixed in 400308f3c2ec18f78690e0e7eedc2fd9fd126f8e