For some applications it is useful to have an estimate of how uncertain
the specific variable is estimated. This could help to act accordingly
e.g. increase the measurement zone if the current estimate is very
uncertain. 

Signed-off-by: Yan Wang <yan.wang@linux.intel.com>

http://www.votchallenge.net/vot2015/dataset.html

1. Multi-tracker classes (multiTracker.cpp)
2. Multi-tracker example (multiTracker_test.cpp)
3. Fixed a rare bug (OpenCL runtime error)

http://www.votchallenge.net/vot2015/dataset.html

1. Multi-tracker classes (multiTracker.cpp)
2. Multi-tracker example (multiTracker_test.cpp)
3. Fixed a rare bug (OpenCL runtime error)