Pre-processor, basic i18nliner.js tie-in

TL;DR: moved/refactored/added a ton of stuff \o/

## highlights

### pre-processor

now you can do block or inline-style t calls. an AST preprocessor converts the former to the latter. block t calls can now be nested, and can also contain other inline handlebars expressions

### i18nliner(.js) dependency

I18nKeyStore now lives in i18nliner.js, and we're now using several other things from there

### readme

fleshed this out a bit (like in the js/rb projects), w/ some important TODOs at the top that will get us to something more useful :)