Mail deletion fixed!

I discovered that it was impossible to delete mails. Nobody reported that, so it went unnoticed. I just fixed that. Also, I disabled people sending in-game mails to me since I read them to rarely. People should rather send me tickets. I will work on the mail system in the future so people can get notification via email when they get an in-game mail and so that emails can me managed on the website, but until this is the case, it will stay as it is.