* signal can only be used in the main thread, leading to an error when StatisticThread is instantiated inside a QThread
* misc fixes on imports and variable names
* Add chunk notion for parallelization
* Allows Node desc to implement custom updateInternals
* CameraInit node implement a specific updateInternals to update the
input image list
* FeatureExtraction, FeatureMatching, DepthMap, DepthMapFilter:
implement parallelization