Mono Fix for Unsafe Mode (#4887)

* Added preprocessor define for C++ if Template Aliases are supported by the compiler

* Revert "Revert "Performance Increase of Vector of Structures using .NET BlockCopy (#4830)""

This reverts commit 1f5eae5d6a.

* Put<T> method was inside #if UNSAFE_BYTEBUFFER which caused compilation failure when building in unsafe mode

* Revert "Added preprocessor define for C++ if Template Aliases are supported by the compiler"

This reverts commit a75af73521.

net/FlatBuffers/Table.cs

@@ -94,6 +94,29 @@ namespace FlatBuffers
             return bb.ToArraySegment(pos, len);
         }
 
+        // Get the data of a vector whoses offset is stored at "offset" in this object as an
+        // T[]. If the vector is not present in the ByteBuffer, then a null value will be
+        // returned.
+        public T[] __vector_as_array<T>(int offset)
+            where T : struct
+        {
+            if(!BitConverter.IsLittleEndian)
+            {
+                throw new NotSupportedException("Getting typed arrays on a Big Endian " +
+                    "system is not support");
+            }
+
+            var o = this.__offset(offset);
+            if (0 == o)
+            {
+                return null;
+            }
+
+            var pos = this.__vector(o);
+            var len = this.__vector_len(o);
+            return bb.ToArray<T>(pos, len);
+        }
+
         // Initialize any Table-derived type to point to the union at the given offset.
         public T __union<T>(int offset) where T : struct, IFlatbufferObject
         {