Dorky chat works. DRY up Makefiles. Fix some crashes.

- Added ttyname to slots, use that instead of m_device to get tty in dorkychat
- Moved /r out of #ifdef SKYNET
- Got dorky.c to compile
- Got a crash when LOGNAME set to invalid Unix account; fixed by throwing in https://github.com/antirez/sds for safe string manipulation
- Added Makefile.common and got rid of repetition in the Makefile.am files
- Added -I to make "include" directory available by default; got rid of "../include/" paths