Total refactoring, changing normalization method, first video enlargement implementation.

Some details:
* Graph construction refactoring
* Removing distinction between Enlargement and Reduction in class structure
* Creating a common class for videos and images
* Implementing Time Shrink function (to be improved)
* First implementation of video resize (not already complete)
* Delegating weights and structure construction to other classes
* Delegating merging/enlarging to an external class