Add --line-number option to hg annotate (issue506)
Line numbers are separated from the last annotation element with a colon,
like with many other commands, e.g. (hg) grep or compiler errors.
Idea and tests by FUJIWARA Katsunori.
abort: Failed to parse .../t/.hg/hgrc
File contains no section headers.
file: .../t/.hg/hgrc, line: 1
'invalid\n'