* nix -> nix-store, fix -> nix-instantiate.

configure.ac

src/Makefile.am

src/nix-instantiate/Makefile.am

src/nix-instantiate/bin2c.c

src/nix-instantiate/eval.cc

src/nix-instantiate/eval.hh

src/nix-instantiate/fix-expr.cc

src/nix-instantiate/fix-expr.hh

src/nix-instantiate/fix.cc

src/nix-instantiate/fix.sdf

src/nix-instantiate/fixexpr.cc

src/nix-instantiate/fixexpr.hh

src/nix-instantiate/parser.cc

src/nix-instantiate/parser.hh

src/nix-instantiate/primops.cc

src/nix-instantiate/primops.hh

src/nix-store/Makefile.am

src/nix-store/dotgraph.cc

src/nix-store/dotgraph.hh

src/nix-store/nix-help.txt