Testing a new way to calculate the branch features.
Bugfix on calc_alpha_sum function. The parent branch was being freed, causing segmentation faults.
Added a function called zero_branch that will guarantee that the data field of the branch will be zero. It is called right after the branch decomposition (ct_decompose). Changed the way that the features are calculated. Instead of iterating through each branch and through the branch map, we just iterate through the branch map once.