This commit hooks the Makefile up to generate a FISH_BUILD_VERSION
symbol and kills off PACKAGE_VERSION in .cpp files.
It also modifies the tarball generation script to add the necessary
version file for releases.
- etc/config.fish and share/config.fish are now "universal" and no longer reference install paths or need to be touched by autotools. They've been removed from config.fish.in to config.fish.
- fish now attempts to determine __fish_datadir and __fish_sysconfdir relative to the path of the fish executable itself (typically by walking up one directory). This means that you can copy the directory hierarchy around and things will still work. The compiled-in paths are used as a backup.
- The fish Xcode project now can build fish natively, without needing autotools.
- Version bumped to 2.0
