base for self-hosted compiler

![dogfood](http://www.mba.yuntech.edu.tw:8080/old_epaper/20120102/image/01-02.gif)

Paves the way to have a self hosted compiler. Any `.mjs` file in the `lib/compiler` directory will be compiled with a bootstrapping javascript only version of metascript (0.0.41 is included as a dev dependency).

This allows to start writing compiler components on metascript, for instance the incremental parser, which will surely help on finding bugs and awkwardnesses in the language itself.