Support for code syntax highlighting

Add optional support for code syntax highlighting using highlighting.js (http://softwaremaniacs.org/soft/highlight/en/)

Issue #4
Remove system proxy usage

This is too slow here on Windows 7. We will later provide a proxy option in the UI.
Support non-latin languages

Better support for non-latin languages.
Remove highlight.pack.js again
Merge branch 'feature/code-highlighting' into develop