updated, refactored and cleaned up devkit packaging and releasing scripts.
added two helper hashing methods and refactored code accordingly.

one is a typed variant of foundation::siphash24(), the other one allows to combine two hashes together.
added dummy file to preserve empty directory in git repository.
fixed crash when the geometry inside an assembly that doesn't contain curves changes between two renders.
Merge branch 'master' of github.com:appleseedhq/appleseed
changed default project setup and simplified code.

frame resolution is now 1024x576 (quarter 2K, 1.78 aspect ratio) and film dimensions are 10.24mm x 5.76mm.
Merge branch 'master' of github.com:appleseedhq/appleseed
cosmetics.
fixed comments.
Added expression examples browser

The expression browser can be shown/hidden by clicking
the "Examples" button.

Signed-off-by: Marius Avram <marius.avram1309@gmail.com>
Merge pull request #519 from marius-avram/examples_browser

Added expression examples browser
Merge pull request #518 from est77/est

Small disney material editor improvements and fixes.
Made refraction tests more robust in microfacet BTDF, fixed bug.
Merge pull request #520 from est77/master

Made refraction tests more robust in microfacet BTDF, fixed bug.
added a unit test.
Merge branch 'master' of github.com:appleseedhq/appleseed
minor code tweaks.
Cosmetic fixes for previous commits

Signed-off-by: Marius Avram <marius.avram1309@gmail.com>
Merge pull request #521 from marius-avram/cosmetic_fixes

Cosmetic fixes for previous commits
simplified code.