Appending a count for filenames that end up being duplicated by

This is a fairly ugly fix for Issue #46. Given the [requirements for identifiers](http://golang.org/ref/spec#Identifiers) in Go, though, I haven't come up with something better. Given a choice, I think this *is* better than not being able to produce code that compiles with this tool, but if someone else has a better idea than this, please share.