fixes #7589 #7588 #7169

• Left menu which is supposed to be more clear and simple. The content itself pretty much stays the same, we want to remove attention from the menus and header etc and let users focus on content
• Better layout for mobile devices
• Includes a fix for UI testing framework where a click was not executed when the element to click is not visible in the viewport
• Includes a new search to search for current menu items, websites and segments (can be activated via shortcut f)
• Unified selectors eg they can be all closed by pressing escape now, they are pretty much always displayed in the top etc
• Many other bugfixes that I noticed while working on it
• Removed a lot of CSS that was duplicated before etc
• Zen Mode was removed as it was supposed to remove the space it needs in the header, as the header doesn't need much space anymore it is no longer needed. We might introduce a ZenMode later at some point which will be eg activated by pressing the key z which will fade out the left menu to have full width content. The left menu is not really needed anymore when using search
• Left Menu plugin was removed as left menu is enabled by default now. There is no way to get back the top menu