Missing / wrong gap sprite image path

[Daniel Wong]

While looking at the logs for this issue: #174

I noticed this on the error log:

*** can't find file [big\bmp\zoom\gap_akuwaraiA4az20.png.png] ***

I don't think this is actually related to the crash, since that animation only involves nanjo and not gap.

Most likely we've included .png in some path when we're not meant to, resulting in the double .png extension.