Add xchat command for ATK (ending AFK)

dotfiles/saturnin/iam.ini

 [iam.saying.like.this]
     afk  = xchat -e -c 'away afk'
     afk  = echo "$(date -Iminutes) | afk one time" >> ~/whatever.log
+    atk  = xchat -e -c 'back'
     atk  = echo "$(date -Iminutes) | apparently knowing my password" >> ~/whatever.log
     gone = xchat -e -c 'nick amahdal|gone'
     gone = echo "$(date -Iminutes) | gone one time" >> ~/whatever.log