ui: add the possiblity to get a date config field Add the method configdate to read a date from configuration. It uses the util.rawparsedate refactored earlier to support all standard date formats.

util: refactor util.parsedate to raises ValueError Split most of util.parsedate in util.rawparsedate and make it raises ValueError instead of error.Abort. The util.parsedate function is now just a shell function converting ValueError to error.Abort for existing users. I need to parse a date from config in a later patch and use util.rawparsedate with ui.configwith which expect a convert that raises ValueError.

match: implement __repr__() and update users (API) fsmonitor and debugignore currently access matcher fields that I would consider implementation details, namely patternspat, includepat, and excludepat. Let' instead implement __repr__() and have the few users use that instead. Marked (API) because the fields can now be None.