File size limit

[Ippo343]

Hi, I tried to use your tool today to split a huge calendar (> 20 MB).
Unfortunately, every year of this calendar had so much data that the split files were still too large to import into google calendar.

I ended up rolling my own for this, but it would be nice if you included the possibility to limit the file size to a given maximum thus splitting the year in two.

Cheers!