debugobsolete: add formatter support (issue5134) It appears that computing index isn't cheap if --rev is specified. That's why "index" field is available only if --index is specified. I've named marker.flags() as "flag" because "flags" implies a list or dict in template world. Thanks to Piotr Listkiewicz for the initial implementation of this patch.

formatter: add function to convert dict to appropriate format This will be used to process key-value pairs by formatter. The default field names and format are derived from the {extras} template keyword. Tests will be added later.

check-code: make dict() pattern less invasive 'foodict(x=y)' should be allowed.