Simplify rules editor

Some new shiny features have been added in this new version.

#37 Extract several values at once
It is now possible to extract several values per rule item. If the expression is returning a list of elements, all of them will be extracted.
For instance, extract all tabs above at once.


#44 #34 Extract URL fields
It is now possible to extract information from URL.

For instance, with a tab opened at :
https://developer.mozilla.org:8080/en-US/search?q=test&r=10#search-results-close-container

An expression such as :
`document.location.search.q` will extract the value of `q` parameter of the URL.
`document.location.pathname.0` will extract the `en-US` URL part.
See related documentation (https://github.com/pdulvp/extract-data#predefined-expressions)

#35 #42 Extract value from input fields
When extracting an `input`, the value will be extracted rather than an empty text. Same as a `meta` tag.

#38 Extract with css selectors rather than XPath
It is now possible to use CSS Selectors as expressions rather than an XPath, allowing easier definition.
For instance, an expression `h2` will retrieve all h2 elements. `h2:first` the first one.
See related documentation (https://github.com/pdulvp/extract-data#predefined-expressions)

#40 Add an Edit button on rule popup
On the view, it is now possible to edit a rule directly with a dedicated button. It is useful as the first one was always selected on option opening.

#47 Open tab on middle click enhancement
When clicking on the JSON button with the middle click, the JSON is opened in a dedicated tab rather than being copied on the clipboard.