* Refactorings.

src/Makefile.am

src/exec.cc

src/exec.hh

src/fix.cc

src/fstate.cc

src/fstate.hh

src/nix.cc

src/normalise.cc

src/normalise.hh

src/normalise.o

src/store.cc

src/test.cc

src/util.cc

substitute.mk