1)Gui changes
 - fit of source image tree to height of scrolling widget
 - checkbox to allow zoom on source tree window
 - entropy/avg.codelength/efficiency indicators and labels improvements
 - combobox to choose method of source tree generetion, bottom-up method
   added
2)Api
 - improved properties/methods to calculate source parameters
 - full implementation of bottom-up method
 - optimization of top-down - now the coding efficiency is comparable with
   bottom-up method, yet the latter is still supreme
TODO
 - input sequence of source