Support flexible pluralization

[ajoslin]

Ref #1. @gertsonderby informed me of how complicated pluralization really is: any range needs to be able to have its own translation.

That's now supported. We're still below 800b payload.

Ranges (inclusive), negative wildcards, and positive wildcards are now supported. A plural value is now just an object with allowed number keys, wildcard keys, and range keys. This means that the array syntax still works.

    PLURALIZED_COMPLEX: {
      '-*': 'Negative fallback with {{count}}.',
      '-3:-6': 'Range -3:-6',
      0: 'Here are {{ count }}',
      1: 'Here is {{ count }}',
      '5:10': 'Five to 10 {{count}}',
      '*': 'And larger: {{ count }}'
    },

This complex value is lazily generated into a function at runtime, only the first time the translation key is requested. It simply becomes something like this:

function anonymous(o,n
/**/) {
if (o[n]) return o[n]
if (n >= -6 && n <= -3) return o["-3:-6"]
if (n >= 5 && n <= 10) return o["5:10"]
return n < 0 ? o["-*"] : o["*"]
}

The wildcards '*' and '-*' default to the largest and smallest values given.