Fixed a subscription button issue after e621 layout update

> Fix for recent website changes ( https://github.com/MilesVII/621watched/pull/1 )
> Updated manifest version

Hotfox for previous issue but addressing cases when there are more than 40 tags in watchlist

A bugfox related to recent e621's minor layout changes. Addresses the issue when new image counter in popup fails to update.

Attempt to fix issue with faulty blacklisting

> Bugfox for critical issue causing watched page not to load additional chunks and freezing new images counter
> New feature: an option to hide subscription buttons in list of tags (refreshes after page reload)
> Added permalink for watched page in popup window.

Foxed issue when the extension breaks if user's blacklist is empty

Fixed the issue with paginator being linked to subscription's search query on every page
Disabled overwriting of search bar contents

Foxed issue with search bar being filled with subscription query on every page
Added hiding of blacklisted posts from additional search queries

Added subscription to complex search queries. Please note that each query makes add-on load a page from e621, so please stick to common tag subscriptions if possible.
I also did rewrite the whole code, now it runs much better when loading multiple pages, and also allows quick modifications in future. I made sure your current subscriptions won't get lost after update, but don't forget to make a backup, just in case.
And there are some minor cosmetic improvements.

Updated configuration to use new 40-tags-per-search-query limit. "Watched" page loading time should decrease, as well as checking for new posts

The extension is updated in order to keep working on new version of e621.net.
Due to new changes on website, the extension can not check new publications for individual tags anymore, but all other functions are saved.

Implemented Import and Export functions that allows you to easily backup, share and migrate your subscriptions!

Implemented improved new image checking: if new posts are found, there is a counter beside to every tag shown in popup window showing amount of new images with this tag

Minor code refactoring for further development

Added check for new posts in popup window. Once plugin icon is clicked, it checks if new posts is available and shows their amount in the window.
List of watched tags is clickable now
Few minor UI improvements: Fixed popup window size on Chrome, added "View watched" button into the window

Improved stability when used with other third-party scripts and handling other unexpected page changes