fast-import: check most prominent commands first

This is not a very important change, and one that I expect to have no performance impact whatsoever, but reading the code bothered me. The parsing of command types in cmd_main() mostly runs in order of most common to least common commands; sure, it's hard to say for sure what the most common are without some type of study, but it seems fairly clear to mark the original four ("blob", "commit", "tag", "reset") as the most prominent. Indeed, the parsing for most other commands were added to later in the list. However, when "ls" was added, it was stuck near the top of the list, with no rationale for that particular location. Move it down to later to appease my Tourette's-like internal twitching that its former location was causing. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>