clipp/clippscript.rb: Add ClippScript::eval_io to evaluate directly to an ouptput stream.
clipp/clippscript.rb: Add ClipScript::Environment::emit to assist plugins.
clipp/ibtxlog_to_pb.rb: Refactor into ClippScript plugin.  RNS-980
clipp/ibtxlog_to_pb.rb: Allow strings to be passed in to from_ibtxlog()
clipp/(clippscript.rb, ibtxlog_to_pb.rb): Move require of 'hash_to_pb' to clippscript.rb.
clipp/ibtxlog_to_pb.rb: Minor cleanup.
clipp/ibaudit_to_pb.rb: Refactor as ClippScript plugin. RNS-980
lua: Use a fixed format string for logging so that the string is not misinterpreted as a format string.