Merge branch 'jk/format-patch-from'

"git format-patch" learned "--from[=whom]" option, which sets the "From: " header to the specified person (or the person who runs the command, if "=whom" part is missing) and move the original author information to an in-body From: header as necessary. * jk/format-patch-from: teach format-patch to place other authors into in-body "From" pretty.c: drop const-ness from pretty_print_context