AutoSync, Header Parameter, Lazy loading

[giospada]

Sorry for making such large pr, but i implemented everything i needed. if you're interest in only some particular features, tell me and i will make a pr only for those features. Features:

• added periodic sync (every n minutes it sync with the anki)
• added header parameter ( if is specified and the cart is not a cloze it will put the value as first field of card)
• lazy loading, is saw that your code load all media all the time, and render each note, i modify this part to first check if the note is modified (with tag, dir and hash) and only then render the note and add the media (speed up my vault witch has a lot of media)

Fixed bugs: the path for the media was hardcoded with windows separator, i add the check for linux/mac users

Let me know

[giospada]

@tansongchen or @JYC333 let me know if i can do something to marge this pr. Or if your are interest or not in maintain this project, please. I'm available for any question or doubt and criticize on this pr.