merge: print status message before launching external merge tool
It seems somewhat common that people run into a merge conflict and
don't notice the launched merge tool, and instead they think hg just
hung. Let's print a message for each file that we launch a GUI merge
tool for.
# See http://EditorConfig.org for the specification
root = true
[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true
[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true