Add TODO item.

Add print-object infrastructure for constituents (used while debugging).

Take advantage of recent ASDF 1.367 enhancements in pathname computation, when available.

Don't normalize away last component in a component name that has dots.

Note: previous commit to u-defpackage was unrelated to specified message.

Functionalize a few macros,
make constituent designators slightly more readable,
fix a typo,
fix a compiler warning in a test.

* Load-source-op planning is broken, especially in how it trickles to
 other systems you depend on. Use load-op for planning, but have it
 perform like load-source-op on our instrumented files.
* Fix :conc-name nil in defstruct

Cleanup: remove an XCVB-only function.
Tweak normalize-pathname-directory-component.
Add TODO: use a real code-walker / CL evaluator

This commit is related to XCVB's change 85a7d660021b5175c131122ef21c2e334afc54ab, which updates XCVB to use ADG's fine-grain-instrumented-load when converting from asdf-to-xcvb.