v0.2.0

• Construction of thumbnail images and image rows removed from render. Thumbnails and rows now only rebuilt when container size changes.
• selectedImages state now set via props change.
• onSelectedImagesChange callback now called directly from onToggleSelected rather than componentWillUpdate. Perviously, a combination of setting selectedImages state and triggering onSelectedImagesChange when componentWillUpdate due to that state change caused a double render.
• Internal image access now via state instead of props.
• Thumbnail generation now atomic function rather than whole array at once.