Reduce default amount of output

[Pennycook]

Feature/behavior summary

The amount of output generated by codebasin for a real project is overwhelming to new users.

We should separate configuration warnings/errors from warnings that occur during file parsing/preprocessing, and redirect the latter to file.

Request attributes

• [ ] Would this be a refactor of existing code?
• [ ] Does this proposal require new package dependencies?
• [ ] Would this change break backwards compatibility?

Related issues

No response

Solution description

• At default verbosity level, write all warnings/errors generated by the preprocessor to an output file.
• Print a single message at the end of a run telling the user if the preprocessor generated any warnings/errors.

Additional notes

Reducing the amount that we print while working our way through the files may make it easier for us to parallelize file handling and/or track progress (i.e., with a progress bar), because users will not be expecting immediate console output.