Update to 0.8.6 and cleanup *.png directory.
[MEMO FOR PREVISOU COMMIT LOG]
I wrote 'SHIKURA' in my previous commit log. it's 'HASEKURA'(right!)
rather than 'SHIKURA'(bad!).
Submitted by: UMENO Takashi <firstname.lastname@example.org>
Approved by: Shinya Esu <email@example.com> (maintainer)
Pointed out by: many many enthusiastic Maria-sama ga Miteru fan.