bugfix interior/exterior handling in material-ref, bugfix file-mesh for STL meshes (was always writing PLY)
add material-glass2, sampler-metropolis, bugfix spotlight angles, fix material ref handling for meshes, fix STL handling in mesh-common, add gen-tangents attrib for PLY meshes
switch to 0.3.0-SNAPSHOT, refactor project structure for literate programming, switch to clojure 1.6.0, move test scene example into index.org, update readme
minor tweaks to example scene