Map arrays.each(), map() and reduce() to lodash implementations
Map objects.pick() and omit() to lodash implementations
Introduce custom functions.apply() with thisArg as last parameter

Lodash implementation takes thisArg as first parameter, which is not very convenient when applying functions instead of methods.
Introduce objects.wrap() to namespace object content
Add FileSaver.js dependency
Introduce loadStringFromFile() to read file content
Introduce saveStringToFile() to trigger file download
Implement import/export UI
Use loadStringFromFile() in ImportController
Use saveStringToFile() in ExportController
Extract app.importAllFromJSON() & .exportAllToJSON() from ui
Move some core modules to core/storage submodule
Introduce exportAll() function to wrap store method
Stub exportAll() and importAll() on storeDouble
Introduce Store#importAll() and exportAll() to import/export all store content
Use Store#importAll() and exportAll() to implement app JSON import/export
Fix timezone issue in tests