Add --resume (and --stop-on-failure) command line options.

Now you don't have to do --stop-on-failure=1.

--resume is documented in the man page and docbook, but basically lets
you resume the last build list quickly without source or metadata
updates, starting from the module that failed. If you want to skip the
failed module, look into --resume-after and --stop-before.


FIXED-IN:1.16