- New fbt package and moved `fbt` and `fg42-new` scripts to the `/bin` directory.
- Created the `fpkg` module in `fbt` in order to separate the straight initialization from FG42 so we don't have to work with free dynamic var/functions.
- Added `debug` support to `fbt` via `:d`
- Added expr evaluation via `:e`
- Added `system` support to `fbt`. We can build different systems with `fbt`. It's more like a generic build tool right now.
- Added `fpkg` related fields to the system struct.