Split image resizing into resize.sh and add cropping support
Use resize.sh in images.sh (to apply cropping)
Crop images
Add a better image of Skylab in orbit

Source: http://www.nasa.gov/externalflash/NASA45/17/17image.html
Fix the caption of figure 373b (wrong in book)

They are listed in order from left to right, not right to left.
Merge fixed caption of figure 373b

Conflicts:
	ch12.htm