The implementation of particle filtering tracker

This contribution aims to implement the tracker based on particle
filtering within a generic tracking API that opencv has. It still
remains to write the documentation.
Minor fix

In response to pull request discussion.
Minor fixes

Some cosmetic fixes in response to the comments made by Vincent Rabaud
in the pull request discussion.
Private commit
Added TrackerSamplerPF

This realization of TrackerSamplerAlgorithm is attempting at perform
sampling with the use of particle filtering.