Support quicklook preview with no leftover files

Hi,

I thought this was a great idea for a utility, thanks! I wanted to avoid file cleanup and a manual call to "qlmanage" or "open" in my own process, so I added an option (-p) that runs Quicklook on a temporary file instead of printing to STDOUT. It's backwards compatible with the existing command usage.

No worries if you don't want this functionality, but it was useful for me.

Thanks again.