Argument flag for user to specify data format on input/output

[mrghosti3]

Would specify for the program what data format type for input/output data:

• Compilation: when flag is specified, it will skip reading "magic bytes" and assume data is formatted as specified. If those arguments are not given than it resumes format detection via "magic bytes";
• Decompilation: outputs data in a specified format (zlib/gzip if flags are given or if none than raw NBT).

Currently supported flags:

• --gzip (alias -g) : for gzipped data
• --zlib : for data archived in ZLib standart