Merge pull request #325 from est77/OSL_work

Write OSL shaders in ProjectFileWriter.
minor cleanups.
bug 321: fixing minor issues
Merge pull request #324 from marius-avram/B312

Instantiation of objects from appleseed.studio
added todo notes (related to issue #327).
building appleseed with SSE/SSE2 instruction sets on 32-bit Linux is no longer supported.
disable SSE-specific assertions when SSE is disabled.
adjust the epsilon value in a unit test in an attempt to make it pass on 32-bit Linux.
More OSL closures work.
Merge pull request #329 from est77/OSL_work

More OSL closures work.
Small formatting fixes to stdosl.h
Copy and cleanup bsdf showdown test.
Split colors and multipliers in Ashikhmin brdf.
Small formatting fix
OSL Ashikhmin BRDF changes. Added Ashikhmin to closures test scene.
Merge pull request #330 from est77/OSL_work

OSL Ashikhmin BRDF work, added (WIP) sample OSL closures scenes.
fixed regression introduced in b310276f19f4be0f808120d8ee88c7c8d567943b ("fixed Qt runtime warning").

QLayout::isEmpty() returns true even if the layout contains items:
https://qt.gitorious.org/qt/qt/source/0315971ee951e9abe7f288564ddf2e81aeed1fd8:src/gui/kernel/qlayout.cpp#L609
delete widgets immediately in appleseed::studio::clear_layout().
added an attribute editor to appleseed.studio.

known issues:
- the initial width of the attribute editor is too small.
- when editing an entity through the entity editor dialog (by double-clicking on the entity), the attribute editor is not updated with the new values after the entity editor dialog is closed.
Merge branch 'master' of github.com:appleseedhq/appleseed