add translatePlural support with compiled plural functions

[kkaefer]

Syntax: "This post has #{comments:1 comment|@ comments}"

[kkaefer]

This allows for varying amounts of plural versions for different languages and uses a similar format as GNU gettext. I.e. there's a plural formula that determines the index of the plural form chosen, based on the number.

[tj]

ah :) good call. perhaps we should try and work it in to the regular translate() call, and just check for the new syntax with numeric values

[kkaefer]

Yeah, I'm not set on the syntax, I've tried various ways and eventually just submitted this. I also plan to integrate lingo with jade so that you can compile language-specific templates and have templates automatically translated. This would be facilitated if jade and lingo would use the same syntax for string interpolation (jade uses #{var}, while lingo uses {var}).

[tj]

yeah that would be sweet, I will try and toy around with this later. I think we should do it just through translate() but the syntax is fine IMO. maybe flip it so plural is first

[kkaefer]

I used the order singular-plural because that seems to be the standard (e.g. gettext, Rails' i18n use that order). I'll write and rewrite some of the translation related code later today.

[kkaefer]

Now uses the absence of the params object to determine whether compilation into a interpolation function is necessary. If so, it automatically finds plurals and creates a special pluralization function for them.