Added some utility functions for tables.
Began implementing Scenario module.

This shall manage the mounting and initialization of the required packages.
Implemented an algorithm to sort dependency lists.

This is needed by the scenario module:
- to work out the correct initialization order
- to detect missing dependencies and cross references
Integrated DSL into Scenario for correct loading.
Prevent base path from being mounted.
Made compatible with PhysFS 2.0.
Implemented several file system iterators.
Merge branch 'master' into feature/scenario
Added much more assert statements to Lua scripts.
Run init scripts in each loaded package.
Finished basic scenario and package handling.

Closes #47