Be explicit when we need (or may need) CL symbols. Also make it so that the LOOM package exports _all_ the symbols exported from its sub-packages, not just the CL ones.

Use CL instead of LOOM in the utilities package – since we haven't actually loaded any of LOOM by the time we define USE-WITH-CL.

flexibility where you need it, and the better performance everywhere else.
Also got rid of the explict listing of every symbol in each package in favor of
a loom.internals:defpackage macro, which creates both cl. and loom. versions of
the package, as well as including the symbols in the overall loom package.

package. It loads all of the modules.