[dev] [sbase] shell scripts

[Strake]

I see some utilities in sbase what could easily be shorter as
shell/awk scripts. Some utilities I sent in earlier, e.g. cut, were
turned down for this reason.

For examples, head:

#!/bin/sh

n=10;

while getopts 'n:' o; do
        case $o in
                (n)     n="$OPTARG";;
        esac
done

shift $(dc -e "$OPTIND 1 - p");

for x in "$@"; do sed ${n}q <"$x"; done

# END

pwd:

#!/bin/sh

echo "$PWD"

#END

Why are these in C?
head.sh now needs dc, but could easily rather use intc [1], which we
could include in sbase.

[1] https://github.com/strake/intc