Add copyright banners to executables
Add acid-env

Add "acid-env" an executable outputing a Bash script setting environment
variables required to access future ACID shell library.
Use Thud

Add dependency on Thud Bash library and include its environment.
Use Thud strict mode

Add acid-strict-env, which uses acid-env and also enables Thud strict
mode. Use it in all ACID executables, replacing manual shell attribute
setting.