Read CRC in Extended Header
-Add classes: Synchsafe, SynchsafeCRC
-ByteArray.cs: Add method "byte[] Reverse(byte[] byteArray)"
-ExtHeader.cs: Add methods "void ReadExtHeader(byte[] byteArray, int pointPosition)", "void ReadCRC(byte[] byteArray, int pointPosition)"
-ID3V2.cs: Delete method "void ReadExtHeader()"
-Add tests