Sprite.markTextureRegionChanged() method added

This method can be used after modifications to a Sprite texture to update the Sprite with a call to onUpdateTextureCoordinates().

E.g. with this method to truncate the Sprite texture:
```java
public static void truncateSpriteTextureRegion(final Sprite pSprite, final ITextureRegion pOriginalTextureRegion, final float pLeftX, final float pRightX, final float pTopY, final float pBottomY, final VertexBufferObjectManager pVertexBufferObjectManager) {
	final float lTruncX, lTruncY, lTruncWidth, lTruncHeight;
	if (pOriginalTextureRegion.isRotated()) {
		lTruncHeight = pOriginalTextureRegion.getWidth() - pLeftX - pRightX;
		lTruncWidth = pOriginalTextureRegion.getHeight() - pTopY - pBottomY;
		lTruncX = pOriginalTextureRegion.getTextureX() + pBottomY;
		lTruncY = pOriginalTextureRegion.getTextureY() + pLeftX;
	} else {
		lTruncHeight = pOriginalTextureRegion.getHeight() - pTopY - pBottomY;
		lTruncWidth = pOriginalTextureRegion.getWidth() - pLeftX - pRightX;
		lTruncX = pOriginalTextureRegion.getTextureX() + pLeftX;
		lTruncY = pOriginalTextureRegion.getTextureY() + pTopY;
	}
	pSprite.getTextureRegion().set(lTruncX, lTruncY, lTruncWidth, lTruncHeight);
	pSprite.markTextureRegionChanged();
	if (pOriginalTextureRegion.isRotated()) {
		pSprite.setWidth(lTruncHeight);
		pSprite.setHeight(lTruncWidth);
	} else {
		pSprite.setWidth(lTruncWidth);
		pSprite.setHeight(lTruncHeight);
	}
}
```