Accept history filename as input

[cespare]

Huffshell didn't pick up my history file when I tried to use it. The docs don't actually say how to run it and there's no huffshell -h or anything with any clues. So I poked around in the source to figure out that it looks for a predefined list of history files. I had to cp ~/.histfile ~/.zsh.history and then Huffshell worked.

What about checking ARGV[0] and if it's provided, use that instead of looking for the builtin list of history files?

[paulmars]

This is a great idea.