import mm2latexinput with cites and details

mm2latexinput.xsl has been taken as base and:

refactored
* indentation
* {"}'s and {'}'s xml-correct

major changes:
* cites are exported as \cite
* details of nodes are exported as text
* only numbered nodes are exported as \chapter, \section, \subsection, \subsubsection
* all nodes structured below are exported as nested \begin/\end{description}
* notes are exported as \todo

minor changes
* esc-sequence for {"}
* modes "trim" for @TEXT and richcontent

it works on my mindmap, further tests have to be done. please report with errors and examples to https://github.com/Docear/Desktop/issues/382