Added basic proof of concept for MGD decoding
Continued work, added SGD decompression
Fixed output header sizes, but it's still bad
Fixed rubocop warnings
Renamed files to match product name
Added support for MGD regions

The game stopped finally stopped crashing.
Now it needs just small tweaks.
Sanitized the way the meta data is kept
Fixed FJSYS file order
Changed format from 1 to 6; switched to RAW

Some titles had problems decoding PNG made with RMagick.
Added silencing warnings from rmagick
Merge pull request #3 from vn-tools/mgd

Added support for MGD encoding and decoding