Add Lua API for accessing packaged game data

[ensisoft]

The project can have references to multiple opaque blobs of data that are defined outside of the game studio project. This could be text, cvs, json, etc.

There needs to be some way for the game to be able to access this data.

• Loading the data files/buffers/handles
• Ability to interpret/access the actual content in some way. Not all possible game data formats can be supported out of the box. A plugin system could be useful here but that's beyond the scope. However for JSON based data we can provide a Lua API around data/reader/writer