fcm conflicts: print progress

[matthewrmshin]

From a user via email:

I'm just working through a sizeable list of conflicts, post merger, and it spurred an idea. It would be really nice to have an idea of how far through the job I was. How about, prior to launching the diff tool a simple message giving x/y where x is the number of the current conflict and y is the total number of conflicts to handle.

Should be a straightforward enhancement.