Merge pull request #101 from jonathantopf/master

Small improvements to dof and light export
Merge pull request #103 from jonathantopf/master

added a new default material and fixed bug in penumbra angle export
Merge pull request #107 from jonathantopf/master

displacement and installation improvements
simplified and cleaned up install_helper.py.
Merge pull request #108 from dictoon/master

simplified and cleaned up install_helper.py.
further cleaned up install_helper.py.
Merge branch 'master' of github.com:jupiter-jazz/Mayaseed
Merge pull request #109 from dictoon/master

Merge branch 'master' of github.com:jupiter-jazz/Mayaseed
further cleaned up the installation scripts.
Merge branch 'master' of github.com:jupiter-jazz/Mayaseed
fixed regression: the installation script wouldn't properly set the environment variables on Windows.
Merge pull request #110 from dictoon/master

Merge branch 'master' of github.com:jupiter-jazz/Mayaseed