Update TODO, with some reindentation.
TODO for define-package, as reaction to recently experienced bug.
Fix for launchpad bug 1247662.

Ensure that SYSTEM-DEFSYSTEM-DEPENDS-ON never gets SLOT-UNBOUND error.
Also cache DEPENDS-ON and WEAKLY-DEPENDS-ON info from DEFSYSTEM.
Bump version to 3.1.0.68
Trivial non-functional cleanups
(improved comments, whitespace, remove doubly exported symbols).
Bump version to 3.1.0.69
XCL cleanups(!): Downgrade *unspecific-pathname-type* due to XCL bug. Hush compile warnings.
Add the same kludge in DIRECTORY-FILES for GCL as for CLISP.
Fix DIRECTORY tests in test-utilities.script.
Bump version to 3.1.0.70
Allow user to specify lisps for upgrade separately from lisps for test.

Added ASDF_UPGRADE_TEST_LISPS environment variable and ulisps local
variable.
Fix test-systed-asdf on Windows (hopefully).
More test cleanups: use assert-compare and assert-equal some more.
Add UIOP to the use-list of ASDF-USER, after testing in cl-test-grid.
Emit an error in an unhandled corner case of run-program.
Bump version to 3.1.0.71
Improved documentation of feature dependencies by Fare, editing by RPG.
Minor nits that makeinfo didn't like.
Putting introspection functions in canonical form.

SYSTEM-DEFSYSTEM-DEPENDS-ON, SYSTEM-DEPENDS-ON, and
SYSTEM-WEAKLY-DEPENDS-ON now always return s-expressions with system
names represented as downcased caps (per COERCE-NAME).
Bump version to 3.1.0.72
Some tweaks to the documentation.
Docstring for REQUIRE-SYSTEM.