v0.2.0: Dirty tracking — dirty-mixin, mark-clean, mark-dirty

- dirty-mixin class with dirty slot (initform t)
- mark-clean clears dirty flag
- mark-dirty sets dirty flag
- 3 tests: default-dirty, clean, dirty-cycle
- ROADMAP.org: v0.2.0 all tasks DONE
- 31 component tests, 100% GREEN

cl-tui.asd

@@ -18,6 +18,7 @@
    (:module "src/components"
     :components
     ((:file "package")
+     (:file "dirty")
      (:file "box" :depends-on ("package"))
      (:file "text" :depends-on ("package" "box")))))
   :in-order-to ((test-op (test-op :cl-tui-tests))))
@@ -34,6 +35,7 @@
     ((:file "tests")))
    (:module "src/components"
     :components
-    ((:file "box-tests"))))
+    ((:file "box-tests")
+     (:file "dirty-tests"))))
   :perform (test-op (o c)
              (uiop:symbol-call :cl-tui-backend-test '#:run!)))