RFE: improve performance of TIFFImageReader::seekToImage

[jandam]

Simple improvement. Please replace TODO at the begining of TIFFImageReader::seekToImage with single line:

if (optimized && imageMetadata != null && initialized && currIndex == imageIndex) return;

Original code:

private void seekToImage(int imageIndex, boolean optimized) throws IIOException {
    checkIndex(imageIndex);

// TODO we should do this initialization just once!!!
...

I suppose that this is simple improvement without side effects.

Thank you.