* Implement `entity' data abstraction to manipulate the microcode's

* Implement `entity' data abstraction to manipulate the microcode's
data type of that name.  Change everything to use it.

* Implement new procedure `gc-clean' that interleaves `gc-flip' and
`trigger-secondary-gc-daemons!' until everything is reclaimed.  Change
`disk-save' to use it.  Cause this operation to be invoked when
running out of memory.

* Add secondary GC daemons to clean up debugging info, and to reset
`prime-number-stream'.

* Extend the procedures `procedure-lambda' and `procedure-environment'
to handle compiled procedures by using debugging information if it is
available.

* Extend all the procedure operations to handle entities.

* Change `pp', `pa', and `->environment' to accept any procedure as an
argument; previously these only accepted compound procedures.

* Change the unsyntaxer to handle compiled expressions by using their
debugging source code if it is available.

* Change name of `*compiler-info/load-on-demand?*' to
`load-debugging-info-on-demand?', and make it be #T by default.

* Change `load' to print "loading..." message for source files as well
as binary files.  These messages are controlled by
`load/suppress-loading-message?'.

* Change `environment-bound-names' to ignore the binding which is used
to hold an environment's package.

* Fix bug in `make-null-interpreter-environment' which prevented it
from being called more than once.