GNU-ify based on GNU-hello, step 1 (configure.ac)
GNU-ify: add AUTHORS,THANKS
GNU-ify: update tests/Makefile.am
GNU-ify: update src/Makefile.am
cleanups: remove 'scripts' directory

There are no add-on scripts for calc (at the moment).
GNU-ify: add auto-generated man page
Merge branch 'better_autotools'
calc: use gnulib closeout module

Protect against write errors at the end of te program,
e.g. 'calc XXX > /dev/full' (which should fail).
system.h: minor improvements