Block structure reuse for multi-rate HEVC encoding

Minor improvement: cleaner file reading.

Block structure reuse for multi-rate HEVC encoding

This version allows to replicate the results from the paper: D. Schroeder, P. Rehm, and E. Steinbach, "Block structure reuse for multi-rate High Efficiency Video Coding", Proc. IEEE ICIP 2015, Sep. 2015, Québec, Canada.