Moved unrelated functions (mainly concerned with working with tar archives) away from mjlog.info.

Added precalculation of sort_key values in mjlog.info.
Switched from lzma to zip compression (~3x speedup on migrating, ~2.5x speedup on reading, ~12% larger databases).
Added collation on sort_key for mode in the database
Added classes for compressed and uncompressed raw logs.
Decoupled iterating over database from log decompression.
Added mjlog.hand module with utilities for decomposing a single suit combination.
Added tests for mjlog.hand.Combination