Update Archi

I thought it was purely a 'principle' thing, but this set -e business definitely demos how and why things can completely spin out of control. Ultimately programs are about control and determinism, and with premature termination you give up both. Build error scripts in place of early termination processing. 

Also, instead of asking the user to change directory, let the script do it by itself.

`$0` expands to the filename of the script, then `dirname` extracts its containing directory. `cd` changes the *current directory* to it. Then, everything else works as before.