grep: add formatter support Several fields are renamed to be consistent with the annotate command, which doesn't mean the last call for the name unification [1]. Actually, I'd rather rename line_number to linenumber, linenum, lineno or line, but I want to port the grep command to formatter first. [1]: https://www.mercurial-scm.org/wiki/GenericTemplatingPlan#Dictionary I don't have any better name for the list of matched/unmatched texts, so they are just called as "texts".

grep: build list of all columns regardless of display options These columns should always be available in JSON or template outputs. The "change" column is excluded because it has no useful data unless --all is specified.