Pure python binding and recover_index_from_blob.py fixes

`recover_index_from_blob.py`:  
* Fixed it in various places now it manages to recover index from data file. Not fast though;
* Allow bases to be passed through command line;
* Improvements to logging.

`blob.py`:  
* Removed check for data header vs index header equality;
* Fixed infinite loop on iteration over broken bases;
* Fixed iteration over removed entries;
* Removed commented code;
* Reformatted code and added comments;

PS. `recover_index_from_blob.py` was broken for about a year.
PPS. `blob.py` is way too "hacky" and probably should not be used in new scripts.