Initial work

Create Reader
Pulled back in Inode decoding and superblock
New Data and Metadata readers
Added getting of id, fragment, and export table data lazily
Added README to squashfs/squashfs

internal/decompress/decompress.go

@@ -0,0 +1,5 @@
+package decompress
+
+type Decompressor interface {
+	Decompress([]byte) ([]byte, error)
+}