* API.styles.*
* API.usercss.*
* API.sync.*
* API.worker.*
* API.updater.*
* simplify db: resolve with result
* remove API.download
* simplify download()
* remove noCode param as it wastes more time/memory on copying
* styleManager: switch style<->data names to reflect their actual contents
* inline method bodies to avoid indirection and enable better autocomplete/hint/jump support in IDE