OUT/Ephemeral: un-crap-ify list comprehensions

The mro-walking list comprehensions in Ephemeral.py don't
always work correctly.  They contain seemingly superfluous
cruft in them.

This patch re-factors them to be more legible, and attempts to take
out the trash.

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>
OUT/Ephemeral: touch-up comments

Touch-ups to outdated, incorrect, and/or incomprehensible comments
and doc-strings.

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>
OUT/Ephemeral: fix lambda expression bug

Oops, this lambda had an argument randomly thrown in for no sane reason,
which was breaking non-weakref-compatible ephemerals entirely.
This fixes them.

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>
OUT/OOParsing: oopsie!

This fixes a hidden syntax error/thinko in a single-item
__slots__ tuple which ommitted the comma, meaning that the
class-level __slots__ attribute was being set to the string
'operator' (not the tuple ( 'operator', )), which was resulting,
ultimately, in wierd GIGO behavior

Signed-off-by: Gregory M. Turner <gmt@be-evil.net>
OUT/RulesParser: __slots__ for EphemerizablePrefixOpProduction

Not sure if this was originally omitted as a work-around for other bugs
or a thinko but it's no longer necessary either way.