add support for textareas, used for various dialog windows on the gui.

The main code to implement the textarea is in console_board.c,
and uses a simple png image with the font, blitting characters
on the designated areas of the main screen.
Additionally we provide some annotations in the image used
as a skin to indicate which areas are used for text messages.
(images will be committed separately).
At the moment the dialog area is only used to display a running
counter, just as a proof of concept.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@97280 65c4cc65-6c06-0410-ace0-fbb531ad65f3