Implement the package library

[mjanicek]

PUC-Lua's standard module library should be implemented in Rembulan in order to allow the execution of non-trivial programs.

This has two facets:

• it should be easy enough to use from the 'host' Java code to bootstrap the Lua environment;
• the require function should expose module loading capabilities to the 'client' Lua programs.

This also requires the implementations of (now missing) functions dofile and loadfile from the basic library.

[mjanicek]

This has now been implemented and merged into master.