Fix build on OSX/Archlinux and add README

- remove SELinux dependency for now
- OSX: find libintl.h
- OSX: fix compile errors
- OSX: use hack around gettext nonsense
- fix gettext on ubuntu
- work around Arch's lack of -ltermcap
- add README.md
Remove more #ifdef dead code
Automate libuv download and build
Set vim binary as default make target
Wrap calls to 'get_mess_env' into LIBINTL #ifdefs