Remove determinate/indeterminate plurals from nouns.

Currently indeterminate plurals are just ignored (unless there is no
determinate form). Also collective has been brought up to same level:

    Noun_Number =
        Singulative -- ĦUTA
      | Collective  -- ĦUT
      | Dual        -- WIDNEJN
      | Plural      -- ĦUTIET
      ;

Finally renamed constructor Num to NumX to avoid warnings about
name clashes with the category.
Smoe cleanup using align-regexp