MebiApi OutputConfig -- Defaults currently override user-set parameters for message output

[thecathe]

Overview

• Default output params in src/output_kind.ml are stored as functions default_level_fun and default_special_fun, and are referenced to by default_level and default_special.
• The intention here is that src/mebi_api.ml can re-define default_level and default_special as specified by the user using set_output_level and set_out_special respectively.
• In the new src/logger.ml we can now use the functor Logger.Make in any of the files that we wish to output messages from -- this allows per-file logging configuration for the programmer, which is intended to be further refined/configured by the user.

Issue

• Since the user configuration comes after compilation, the loggers made by Logger.Make will already be hard-coded with whatever defaults are in src/output_kind.ml, effectively removing the ability for user configuration.

Proposed Solution

• Rework the functor Make in src/output_mode.ml to take references to the configured functions in src/output_kind.ml, rather than the functions themselves.