Fix file uploads on new selenium with firefox (#15)

* Fix file uploads on new selenium with firefox

* Add docs and fix docs

* Better docs

Add close command for a window (#14)

Merge pull request #10 from alexpott/w3c-session-fix

Fix w3c false issues

Update LegacyWindow.php (#9)

Fix it so that it works!

Fix function signature for element properties

Fixes to function signatures (#8)

Fix the function signature for postActions (#7)

Implementation review wrt 25 Oct 2022 W3C docs

* refs instaclick#119 - updating phpdocs for focusWindow

POST /window must define handle first for Selenium 3.x and Firefox

improve readability when extracting from value/result