WriteStream are now subclasses of it.
* Added new methods eos(), ioFailed(), clearIOFailed() to
all streams. This allows better error checking.
* SaveFile classes take advantage of these new standard
stream APIS
* Removed File::gets()
* Added SeekableReadStream::readLine() (replaces File::gets)
* Added WriteStream::writeString, for convenience
svn-id: r17752
o extend MemoryReadStream with XOR facility
o implement MemoryWriteStream
o _fileHandle now is a reference to BaseScummFile class and is created on the fly
o implement ScummNESFile class which is basically extract_mm_nes utility
o update NES MM md5's due to above changes
NOTE: to run MM NES now you need to remove *.LFL files and (probably) rename
ROM to standard conventional name 'Maniac Mansion (XXX).nes'
svn-id: r17300
