[FIX] httpd:  Null-terminate options
httpd:  Define STRLEN() and STR_LEN() locally
command:  Add optional flags argument
command:  Add errors unit, usage()
command:  Report and handle errors by default
Merge branch 'get_option-usage'
httpd:  Axe redundant get_option() error checks

The default case can only occur from a programmer error, not on bad user
input, and the abort() is clear enough.