• Update to version 2.73a
• Use blender's installation process instead of using our own

This blender release comes with a couple of major improvements, such as

• improved volume rendering and area light shading via cycles
• better fullscreen support for the user interface
• a major upgrade of the grease pencil tool (especially stroke animations)
• improved motion tracking
• and many more

Changelog: http://wiki.blender.org/index.php/Dev:Ref/Release_Notes/2.73