Univention Corporate Server 4.2 erratum 470 (security)

This update addresses the following issues:
* Double free vulnerability on crafted image (CVE-2016-1516)
* out-of-bounds write error in the function FillColorRow1 (CVE-2017-12597)
* out-of-bounds read error in the cv::RBaseStream::readBlock function
  (CVE-2017-12598)
* out-of-bounds read error in the function icvCvt_BGRA2BGR_8u_C4C3R
  (CVE-2017-12599)
* buffer overflow in the cv::BmpDecoder::readData function (CVE-2017-12601)
* invalid write in the cv::RLByteStream::getBytes function (CVE-2017-12603)
* out-of-bounds write error in the function FillUniColor (CVE-2017-12604)
* out-of-bounds write error in the function FillColorRow8 (CVE-2017-12605)
* out-of-bounds write error in the function FillColorRow4 (CVE-2017-12606)
* Heap-based buffer over-write in modules/imgcodecs/src/grfmt_pxm.cpp
  (CVE-2017-12862)
* Integer overflow in PxMDecoder::readData function in
  imgcodecs/src/grfmt_pxm.cpp (CVE-2017-12863)
* Integer overflow in ReadNumber function in
  opencv/modules/imgcodecs/src/grfmt_pxm.cpp (CVE-2017-12864)
* out-of-bounds write error in the function FillColorRow1 (CVE-2017-14136)
* Buffer Overflow in the cv::PxMDecoder::readData function in grfmt_pxm.cpp
  (CVE-2017-17760)
* out of bounds write in functions FillUniColor and FillUniGray in
  opencv/modules/imgcodecs/src/utils.cpp (CVE-2017-1000450)
* Heap-based buffer overflow in cv::Jpeg2KDecoder::readComponent8u
  (CVE-2018-5268)
* Assertion failure due to incorrect integer cast (CVE-2018-5269)