updated doc-block
replaced "head -c" with dd again for compatibility reasons, use bs=1 and count=$value this time to hopefully prevent file truncation
Added new arguments to match official version.

From official repo:
(985e6f7) Add support for line, type, and name command line args.
Updated README to include new options
Merge pull request #10 from dhowden/extra-options

Added new arguments to match official version.
Close stdin/out/err before forking.

This ensures that if the parent shell exits, the tty can be closed (e.g.
when running in screen the window will close automatically instead of
waiting for all forked rmate processes to exit).
Merge pull request #12 from tornewuff/detach_better

Close stdin/out/err before forking.