Fix bug with fade when rapidly changing scenes (fixes #73).
Fix bug with fade when rapidly changing scenes (fixes #73).

Benvii/pannellum,ywjrg/pannellum,eric-seekas/pannellum,psteph801/psteph801.github.io,psteph801/psteph801.github.io,quentinyang/pannellum,psteph801/psteph801.github.io,riuson/pannellum,mpetroff/pannellum,mpetroff/pannellum,riuson/pannellum,riuson/pannellum,Benvii/pannellum,eric-seekas/pannellum,psteph801/psteph801.github.io,eric-seekas/pannellum,quentinyang/pannellum,mpetroff/pannellum,ywjrg/pannellum,quentinyang/pannellum,quentinyang/pannellum,mpetroff/pannellum,ywjrg/pannellum,riuson/pannellum,ywjrg/pannellum,Benvii/pannellum,eric-seekas/pannellum,Benvii/pannellum