And don't require the module.o to already exist: link against generated .o files.

Includes primitive attempt to place fragments into appropriate framework to
compile them.

We had example names like "example-opt.h-opt_parse", which got trimmed to
"example-opt".  By using a basename of example-opt.h-opt_parse.c, we only
strip the final ".c" not the middle ".h".

Don't allow NULL descs, and put them in macro.  Users can use "", but make
sure it's explicit, not an accidental omission.
Use errx() instead of assert() for API usage errors.
Rename opt_flags to opt_type.

I still don't like the duplication, but it's clearer and not much longer.

longidx is not updated in this case.  We should open-code option parsing.

This is more explicit than separate short and long (great for grep!) and
simpler.

This includes renaming ATTRIBUTE_UNLIKELY_FUNCTION to ATTRIBUTE_COLD,
and removing unlikely_func macro from ccan/likely.

Valgrind was giving a spurious error.

We were getting occasional failures: if all values are the same it's a 1-line
graph and there's no "|" anywhere.

Currently they sit in each module.

Macro packages do this.

This is a precursor to doing something useful with them.

As per-tdb's tools.

We want it to complain if it's wrong...

That way we match our comment about optimal tally_new() arg matching histogram height.

Including pretty graphs!

Not as trivial as you might think, with overflow and underflow.