Eliminate unnecessary 'Proxy' with 'SimpleCall's.

I originally used 'Proxy (SimpleCall ...)' for the type of
'SimpleCall' calls, since the term is irrelevant. But this just
complicates things unnecessarily.
Rename logging and memoization functions.

Use verb names instead of noun names.
CP [reorg modules]: rename base folders.
CP [reorg modules]: rename base module string in files.
CP [reorg modules]: move files.
CP [reorg modules]: fix module names in files.
Rename package from 'logtree' to 'decorator'.

Now the package and module structure reflect that
this is about decorators, not logging specifically.
Of course, it was about logging when I started ...