ESM reader / writer support for Oblivion

Objective here is have re-write our current esmreader/writer to support the bare necessity to parse Oblivion (TES4) which also supports Morrowind (TES3). Keep it forward thinking with additional format changes that come in later games.

We do not need to support all TES4 features, but enough has to be there to support terrain rendering and everything that our current esmreader/writer supports.