Unsurprise linecount

Principle of least surprise says that a tool should do the least surprising thing.

I was puzzled when copyright-updater wasn't updating the copyrights in my files.  I had to dig through the source to figure out why.  And the reason is that the line limit is set much too low.

Any line limit will be surprising if it's unexpected.  Even at 200 lines, some files may get their copyrights set while others, (silently), do not.

I like the idea of being able to cut down the limit as a speed optimization, but I don't think there should be any limit by default.  So I've invented the linecount=0 semantic to mean "no limit" and I've set the limit to zero.