Very minor change to the mini chat icon

As reported in https://zandronum.com/tracker/view.php?id=4295, the mini chat icon appears cut off on the scoreboard, which also seems to only happen in the software renderer. This is because the mini chat icon is 10 pixels tall, unlike the other mini icons which are 9 pixels tall. As such, I added an improved version of the mini chat icon made by unknownna which has a height of 9 pixels. While I'm at it, I also moved tlkmini and rdytogo out of the sprites folder and into the graphics folder, where they belong.