Close file handle

[GPSHansl]

closing file handle allows renaming of file on windows
the final filename timestamp will no longer contain ":" chars
use own dialect to allow "semicolons"

[svalouch]

Ah, Windows.

I'm okay changing the file handling to use close() and in principle also changing the file name to be valid on NTFS, but that would be a breaking change and I'm not planning on a release. That being said, it's broken on windows. I'll think about it.

But what's the reasoning behind changing the delimiter? Most tools allow you to specify which is used for reading, so this seems unnecessary to me.