Merge pull request #6 from adammck/fix_for_go12

Fix for Go v1
Support non-standard baud rates

This sets the baud rate using the IOSSIOSPEED ioctl, rather than as part
of the termios options, which allows arbitrary speeds.
Update docs for OpenOptions.BaudRate
Merge branch 'nonstandard_baud_rates'
Remove 'serial' subdir
Update README
Remove Arduino stuff

This has nothing to do with the Go package.