Make sure, that new Buffer views are used in PrimitiveBlocks from BufferAccess

[tpietzsch]

MemCopy implementations that copy from/to Buffers currently use the stateful Buffer APIs, e.g.

imglib2/src/main/java/net/imglib2/blocks/MemCopy.java

Lines 477 to 484 in 4f41d20

	class MemCopyByteBufferToArray implements MemCopy< ByteBuffer, byte[] >
	{
	@Override
	public void copyForward( final ByteBuffer src, final int srcPos, final byte[] dest, final int destPos, final int length )
	{
	src.position( srcPos );
	src.get( dest, destPos, length );
	}

To make sure this works in multi-threaded scenarios, new Buffer views should be used in every PrimitiveBlocks instance.
For example, this

imglib2/src/main/java/net/imglib2/blocks/CellImgRangeCopier.java

Line 221 in 4f41d20

final S src = ( S ) ( ( ArrayDataAccess< ? > ) cellAccess.get().getData() ).getCurrentStorageArray();

should be something like

final S src = ( S ) ( ( ArrayDataAccess< ? > ) cellAccess.get().getData().createView( this ) ).getCurrentStorageArray();

Alternatively, we should make sure that createView() is called when getting the BufferAccess from an image. (For example, for ArrayImg that should be already the case.)

Even better would be to move to Java 9+, where absolute bulk put/get methods are available in Buffer and we can avoid the stateful API in MemCopy.