Refactoring: no use of profiles

Instead store state in /opt/ceh/installed and use indirect gcroot links.
Refactoring continued: GHC fixed
Refactoring continued: ceh_nixpkgs_install fixed
Refactoring continued: update documentation
Refactoring continued: manpages
Refactoring continued: ceh-purge.sh fix
Refactoring continued: ghc-build-shell.pl fixed