removed unused #include statement.
added get_factory() and get_source_object() to foundation::Lazy.
Cosmetic fixed from previous PR

Signed-off-by: Marius Avram <marius.avram1309@gmail.com>
Merge pull request #533 from marius-avram/cosmetic_fixes2

Cosmetic fixed from previous PR
multiple assemblies with the exact same geometry will now share a single triangle tree.
Merge branch 'master' of github.com:appleseedhq/appleseed
fixed compilation on linux.
fixed compilation on linux.
cosmetics.
Fixed Disney BRDF bug when base color is black.
Fixed error in last commit
Fix compile error.