Use `futile.logger` to within `Cyclops`

[msuchard]

Tasks (this is the usual contract):

• [ ] Refactor message-level check into *Logger class. May address this later, since Cyclops only constructs strings if message-level <= threshold for efficiency.
• [ ] Delegate printing of everything to flog commands

Alternative (ignoring usual contract for efficiency):

• [ ] Pass message-level from currently active flog
• [ ] Delegate printing to flog command of appropriate level

Note: this alternative is probably what is already happening by wrapping Rcpp::Rcout output