added sha512 support (RhBug:1082658)
Fix pool_split_evr's handling of EVRs without releases.

Typically, advisories may have EVRs like "1.4".
reldep: constructor accepts unicode strings (RhBug:1124968)
improved performance of python sequence iteration (RhBug:1109554)
iutil-py: removed pyseq_to_packagelist function