Compared to 1.15-pre:

• Improvements to OneDrive Authentication
• Minor bug fixes
• Merged changes for 1.14-r2..r4 to comply with Google policies

From 1.15:

• Added background synchronization: Keepass2Android now uses the internal cache copy of the database for loading and saving to make these operations faster. After this, synchronization with the remote database is started.
• Added user preferences to control behavior of background synchronization. You can enable periodic background synchronization and control if synchronization should be performed always or only in Wi-Fi networks.
• Improvements to URL handling for WebDav with non-ASCII characters