Add a good conf file backup.
Add validation check to the parameter settings.

Number check
Invalid char check
Negative number check...
add feature of blind zone settings. not complete.

Need to finish the core function in the tracking alg filter.
The GUI, config file logic and controller logic are completed without tested.
Change a function name.
Now the software can set the blind zone.

But we don't have a feature that clear all the blind zone...
Now the blind zone feature are almost completed.

we keep a list of four points both in configmanager and tracking filter to store the blind zones. And we construct a mask related to each blind zone. The mask is 0 in the blind zone and 1 otherwise. We multiply the mask with frame we got and transform it to the tracking algorithm to implement the blind zone feature.
Merge branch 'feature-blindzone' into develop