Fix issue 313 & 314

- Add package table in each scope, due to check which package/module name is accessible via imports.
- Renamed/Selective imports no longer create aliases for the introduced names.
- Module Scope Operator with fully qualified name no longer works.
Add workaround for (imp).mangleof and (imp).stringof
Fix existing tests and add new ones for import mechanism
fix Issue 313 - [module] Fully qualified names bypass private imports
fix Issue 314 - [module] Static, renamed, and selective imports are always public