Fix tiff loader for tiffs with transparency

[akoch-yatta]

The Tiff loading seems to break when loading a tiff with included transparency, e.g. tiff_image.zip

Error

 org.eclipse.swt.SWTException: Unsupported color depth
	at org.eclipse.swt.SWT.error(SWT.java:4932)
	at org.eclipse.swt.SWT.error(SWT.java:4847)
	at org.eclipse.swt.SWT.error(SWT.java:4818)
	at org.eclipse.swt.internal.image.TIFFDirectory.parseEntries(TIFFDirectory.java:374)
	at org.eclipse.swt.internal.image.TIFFDirectory.read(TIFFDirectory.java:450)
	at org.eclipse.swt.internal.image.TIFFFileFormat.loadFromByteStream(TIFFFileFormat.java:65)
	at org.eclipse.swt.internal.image.FileFormat.loadFromStream(FileFormat.java:77)
	at org.eclipse.swt.internal.image.FileFormat.load(FileFormat.java:99)
	at org.eclipse.swt.graphics.ImageLoader.load(ImageLoader.java:154)
	at org.eclipse.swt.graphics.ImageLoader.load(ImageLoader.java:179)
	at org.eclipse.swt.graphics.ImageDataLoader.load(ImageDataLoader.java:29)
	at org.eclipse.swt.graphics.ImageData.<init>(ImageData.java:380)
	at org.eclipse.swt.graphics.Image$ImageFileNameProviderWrapper.getImageMetadata(Image.java:2147)
	at org.eclipse.swt.graphics.Image.getImageMetadata(Image.java:782)
	at org.eclipse.swt.graphics.Image.win32_getHandle(Image.java:821)
	at org.eclipse.swt.graphics.Image.createGdipImage(Image.java:1009)
	at org.eclipse.swt.graphics.GC.drawImage(GC.java:1026)
	at org.eclipse.swt.graphics.GC.drawImage(GC.java:1020)
	at org.eclipse.draw2d.SWTGraphics.drawImage(SWTGraphics.java:466)
	at org.eclipse.draw2d.ScaledGraphics.drawImage(ScaledGraphics.java:270)
	at org.eclipse.draw2d.Graphics.drawImage(Graphics.java:176)

Snippet to reproduce

public class Snippet1 {

public static void main (String [] args) {
	new ImageLoader().load("c:\\Users\\akoch\\Downloads\\tiff_image.tiff");
}
}

[ShahzaibIbrahim]

After working on this for few hours, I tried updating the read method to detect samplesPerPixel == 4 and allocate image.alphaData to hold per-pixel alpha values. But in the process I could see the image but still losing the transparency. On the hindsight, this class was last changed 22 years ago and since then it has only supported either gray scale or 3 sample per pixel images (eg. RGB)