Log.get_prefix_builder

drop the section feature and allow for way shorter log prefix

I dropped sections because they make the codebase hard to maintain.

Call Log.set_prefix_builder with whatever function creates your log prefix.
Log.short_prefix_builder is provided as a ready-to-use example.

updated .gitignore

updated .gitignore

updated

Merge branch 'acm-master'

added the possibility to setup and clear a prefix

the prefix is a constant string that will appear on all log lines
just after the log level, as-is, with no extra formatting of the prefix string

updated

exposed string_of_level and added level_of_string

new version