rename of teaser_images

associate the teaser images to their paper titles
also added an image for paper "A Hardware Unit for Fast SAH-optimised
BVH Construction"
update teaser_images/README.md

regenerated the file
update teaser_images\readme_gen.py & teaser_images\README.md

added a line describing filename under each image
fix teaser_images/readme
fix filename in teaser_images
regenerate teaser_images/README.md
Merge pull request #1 from BachiLi/master

association of teaser images with their titles