http progress indicators

Description

What was at first a light-hearted attempt at getting more info from http fetching turned into an important UI-consideration, after a message on the list prompted serious discussion on how to make git more responsive and informative when fetching over http.

Status

The currently implemented guidelines for displaying progress status are:

• all messages look like “Fetching[]: xx%”, with [] being
  • pack index: " pack index (n)"
  • pack: " pack (n of N)"