Humanize Inflections

As discussed and described in the old Rails Trac already, it would be good to be able to specify custom inflection rules and strings for #humanize:

Inflector.inflections do |inflect|
  inflect.human /_cnt$/i, '\1_count'
  inflect.human "legacy_col_person_name", "Name"
  inflect.human "strt_dt" => "Start date",
                "upd_dt"  => "Updated date"
end

"the_cnt".humanize #=> "The count"
"upd_dt".humanize  #=> "Updated date"

I hope this will be accepted this time as it is (at least for me) an important feature and quite easy to implement.

Find attached a patch against edge, including tests.