v0.6.0

See ChangeLog below for details but most importantly:

• added Items construct and corresponding test (for usage)
• added Seq_'s .data construct to perform basic inner/outer/left/right joins and pivots
• added basics stats for quick EDA
• removed Unit_ (use aptus. now)
• removed old deprecated methods (thnIf, ...),
• fixed bugs: padLeftZeros and trimLines bugs in String_
• fixed sbt assembly in build
• added Java*_ extension methods
• added more tests

Full Changelog: v0.5.2...v0.6.0