Go Serial library

Currently, it only supports Linux and is mostly tested on ARM and x86_64 architectures. There's no dependency on CGO and it directly calls Linux kernel.

The implementation uses some public-domain headers from musl-libc, manually converted to Go.

Currently, there's no support for non-standard baud rates, like 250000, but they will likely be implemented, since many devices based on Ardiono will use it to reduce error ratio from jitter.