"Save As..." Option / New Files from Scratch / Plain SNBT File Support

[Offroaders123]

Add the ability to:

• Save your current edits to a brand new file, without writing to the original one you opened it from.
• Write a new file to disk based on your own content, from scratch. Right now you can only edit something after having opened another file.
• Open plain SNBT text files, and allow you to save them back again just as text (expected), but also with the "Save As..." feature to binary NBT as well, including the options provided by the "Format Options" dialog.

[Offroaders123]

Oh yeah, keyboard shortcuts!