7.5.4.3 shell-parser: emit Bourne shell script

This will produce a main() procedure that emits a shell script that will parse the command line options. That script can be emitted to stdout or inserted or substituted into a pre-existing shell script file. Improbable markers are used to identify previously inserted parsing text:

# # # # # # # # # # -- do not modify this marker --

The program is also pretty insistent upon starting its parsing script on the second line.