Initial Release

And probably the final release. I can not bother to add support for MCPE worlds. This currently supports all Java edition NBT based files, such as .nbt, .dat, .structure
Supports copying, pasting, cloning, creating and deleting tags.
Renaming and Editing tags is not yet properly implemented. Double clicking a tag throws an exception (supposed to open the edit tag menu)
Saving the nbt files works fine.