Limit max number of thumbnails to 60

[natural-harmonia-gropius]

Also optimized the default options.interval and initialized the network

[natural-harmonia-gropius]

32px per thumbnail for 1920px width monitor, I think that enough.

[po5]

Thanks! I'll probably change the default and add an option for the max number of thumbs, because one thumbnail every 2 minutes (for a 2h movie) feels too infrequent to me.