add flatbuffers

commit 6da1cf79d90eb242e7da5318241d42279a3df3ba
Author: Max Burke <max@urbanlogiq.com>
Date:   Sun Jan 19 14:47:28 2020 -0800

    [rust] Add use declarations to Rust-generated bindings for imported FB definitions (#5645)

    * Bugfix for Rust generation of union fields named with language keywords

flatbuffers/swift/Sources/FlatBuffers/FlatBuffersUtils.swift

@@ -0,0 +1,16 @@
+import Foundation
+
+public final class FlatBuffersUtils {
+    
+    /// Gets the size of the prefix
+    /// - Parameter bb: Flatbuffer object
+    public static func getSizePrefix(bb: ByteBuffer) -> Int32 {
+        return bb.read(def: Int32.self, position: bb.reader)
+    }
+    
+    /// Removes the prefix by duplicating the Flatbuffer
+    /// - Parameter bb: Flatbuffer object
+    public static func removeSizePrefix(bb: ByteBuffer) -> ByteBuffer {
+        return bb.duplicate(removing: MemoryLayout<Int32>.size)
+    }
+}