Fixes & improvements

• Added Chinese(Simplified) translation (#558)
• Fix selected list font color on edit screen. #526 (#559)
• Fix & improve FTS. Implements #552 (#556)

Maintenance

• Add INSTANCE_ORIGINAL_TIME column to instances. Implements #564 (#565)
• remove changelog and redirect to Github releases. Implements #393 (#573)
• Update color-picker to 1.1. Implements #568 (#569)
• Update java source and target compatibility to 1.8. Start to use lambda. #498 (#499)
• Refactor entity processor chain. Implements #533 (#551)
• Update minSdkLevel to 15. Remove all obsolete code and resources. #392 (#549)
• Replace tabs with 4 spaces in java files. Update code style to not keep tabs. #523 (#546)
• Introduce TransactionEndTask. Implements #531 (#532)
• Revisit Relation contract. Implements #457 (#524)