This commit adds cross-device sync ability for two plugins: reading statistics and vocabulary builder. It relies on user setting up a Cloud server (DropBox and WebDAV but not FTP though) and designating a path. Behind the curtains sqlite databases are being passed around and updated.
UI-wise, for the statistics plugin, two new menu items Synchronize now and Cloud sync to set it up (might not be the best wording) are added. As for vocabulary builder, a similar Cloud sync button is added to the menu and a shortcut icon button to Synchronize now is pinned at the bottom corner.
CloudStorage new features: WebDAV creating folders and uploading files. And a new widget-like sync server chooser. In the end I decided not to add automatic sync, as the SQL commands part seem a bit much.
* Add a new socketutil module with a few helper functions that allow us to:
* Always use a sane User-Agent (previously, only Wikipedia did so)
* Set timeouts in an almost sane manner. Doing it explicitly prevents an interaction with KOSync that does crazy stuff I don't even want to try to understand.
* Unified said timeouts based on the request's intended usage (except for Wikipedia, which already had meaningful timeout values).
* Stopped using LuaSec directly, LuaSocket defers to LuaSec sanely on its own. Everything now transparently supports HTTPS without code duplication.
Option to synchronize files in local koreader folder with folder on Dropbox. All files that aren't on the local disk will be downloaded. Files with different sizes will also be downloaded and overwritten.
The download process can be paused or stopped at any time (similar to downloading images in Wikipedia).
Synchronize and settings are available after long press in dropbox account in Cloud storage.
Limitations: Only one folder (without subfolders) can be synchronize with one folder on local storage.
Option to show all files in cloudstorage also not supported by KOReader. We can also download any file.
To show all files in CS we need to enable option Show unsupported files in file manager (introducing in #5129)
Close: #5006
