BaseKit Data Tweaks.

Add a Description method to get a string representation of the bytes in the buffer.

* BaseKit/source/Data.h
* BaseKit/source/Data.cpp

Add a function for querying if a DataReader is at the end of the buffer and add a function to advance the position, which returns the original position so we can make a sub-stream from it.

* BaseKit/source/DataReader.h
* BaseKit/source/DataReader.cpp

Add <string> to the precompiled header.

* BaseKit/source/BaseKit.pch