v0.2.0: Box renderable — border, background, and title

- Box class with border-style, title, fg/bg slots
- render-box dispatches through backend protocol
- draw-border for borders, draw-rect for background
- draw-text for title below top border
- 7 tests: defaults, border, background, title, no-border,
  zero-size, minimum-size
- 13 assertions, 100% GREEN
- ASDF updated with src/components module
- modern-backend now accepts :output-stream initarg

backend/modern.lisp

@@ -113,12 +113,13 @@
 
 (defclass modern-backend (backend)
   ((output-stream :initform *standard-output*
+                  :initarg :output-stream
                   :accessor backend-output-stream)
    (in-sync-p :initform nil :accessor in-sync-p)))
 
-(defun make-modern-backend (&key color-palette)
+(defun make-modern-backend (&key color-palette output-stream)
   (declare (ignore color-palette))
-  (make-instance 'modern-backend))
+  (make-instance 'modern-backend :output-stream (or output-stream *standard-output*)))
 
 (defmethod initialize-backend ((b modern-backend))
   ;; Enter raw mode, enable mouse, bracketed paste