updated license notice.
removed old jupiter jazz logos.
Merge pull request #445 from est77/master

Fixed bug when using refraction closure from OSL.
removed black variants of appleseed logos.
updated appleseed logos (logo pack 1.3).
Merge branch 'master' of github.com:appleseedhq/appleseed
fixed logo pack license.
adjusted appleseed website favicon.
updated favicon and Twitter profile pictures.
Added option to not hide symbols, for old gcc versions.
Small fixes and formatting changes.
Merge pull request #446 from est77/gcc_hide_symbols

gcc hide symbols
updated logo in appleseed.studio's About dialog.
set appleseed.studio's application icon on Windows.
Merge branch 'master' of github.com:appleseedhq/appleseed
removed stub file.
enable parsing by scripts/appleseed.gather.py.
fixed test program for standalone appleseed.foundation library.
fixed logo URL in README.md file.
updated link to MIT license in README.md file.