added callCapability parameter so that 'telekinect' is not hardcoded
removed passing callCapability individually to messagesView because callCapability is now part of AppState
draw the composingCanvas in the MessagesView::draw() now. also do not save callCapability as a string member of MessagesView; instead refer to it as a member of AppState
refactored the friend availability status icons into separate functions and made a static method for the FriendView to draw a legend explaining these icons
draw the legend to explain the availability icons in the FriendsView
do not pass the callCapability to GUI separately because it is part of the appState now