pkSetGlobal function implemented to support adding globals from the
native interface. Also the PKVM slots doesn't need a runtime anymore to
use them (see math.PI global to see how it works).
- all import statement (native or script file) have the same syntax
- allow relative (including parent directory) imports
- cyclic imports are handled by caching the scripts
- `import foo` can potentially import `<searchpath>/foo/_init.pk`
- * import are not supported anymore
at this point only binary operators are implemented, unary are yet
to do.
getters and setters for native classes implemented with the names
@getter, and @setter (however the names or arity aren't validated
at the moment TODO:)
