Strictly separate app from window. Add some valadocs documentation.

 * Add wrapper for SourceView to add dirty flag.
 * Get rid of some valac warnings (access with this to static members).
 * Some minor fixes.
Update code documentation.

 * All but Guanako and UiElement derived classes completed.
 * Work forward to fix #6.
Merge branch 'valadocs'

Conflicts:
	src/main.vala
	src/ui_main.vala

 * Drop unnecessary CodeView class (wrapper for Gtk.SourceView and
   Gtk.SourceBuffer).