This doesn't make it much better but allows to build a package
libicinga-vendor-php placing those files to /usr/share/php/IcingaVendor
or similar.
refs #4075
we use the following vendor libraries:
- Markdown.php for on-the-fly creation of documentation
- htmlpurifier for sane HTML output
- lessphp for on-the-fly creation of css out of less files
- tcpdf for pdf generation in the backend
refs #4212