* 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.
Adds joplin support, fixes https://github.com/koreader/koreader/issues/5086
Changes
-adds a submenu to evernote menu
- -Joplin
|-Set IP and port
|-Set authorization token
|-Export to Joplin
|-Help
-adds EvernoteExporter:exportBooknotesToJoplin()
-adds JoplinClient.lua
-modifies html_export, txt_export and joplin_export flags to work with each other. (eg if user selects one others deactivated)
