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.

# should print nothing
# should print ? b/x
? b/x
# should print A b/x
A b/x
# should forget b/x
forgetting b/x
# should print nothing