Added the FileContainer and VirtualFile classes

|SOURCE|
[Common/System/FileContainer]
* The base class for various file container types, such as the local file
  system using the OS's file API and compressed archives
* Files are stored and accessed by name
[Common/System/FileSystem]
* Added an array of VirtualFile elements which will hold all the files in a
  virtual format
[Common/System/VirtualFile]
* Stubbed-out the virtual member functions
* Added a GetName member function, as virtual files co-exist in a larger,
  distributed echosphere than loading files from mass storage