Improve UI to be more fluent.

I have some ideas on how to make the UI for discord a bit more reactive and clean.

- The ability to collapse the channel list in servers along with the user list.

- The ability for more elements to react to mouse hover (Example: Server chat categories are collapsed hovering the mouse animates them open until hover stops, hover on the edge of the channel list "if you take the first idea" or hover over the edge of the user list that element slides into view if the element is collapsed) so we have the option to either pin it like we do now or keep collapsed until needed without having to re-pin it.

- themes other than dark and light allow a color picker for custom CSS in the user options that follows to other clients and saves when cache is cleared (server side basically), user uploaded image for custom client wallpaper, and a transparency slider for elements of the discord window.