Short messages border display issue

[andmcadams]

Short messages (0-2 characters) sometimes have messed up message bubbles due to the way the tk borderImage works. Ideally, I would solve this by changing the imageBorder itself and make it fit all messages. This may be partially solved when dealing with emojis, as messages are typically very short when they are a few emojis long (emojis are typically removed from the text before displaying).