Implements fat from butchered animals.

Originally suggested on the forums.

Creatures can now have a ````MF_FAT```` flag. This makes them produce raw fat when butchered.

new food item ````fat```` which is obtained by butchering creatures that have the ````MF_FAT```` flag
new food item ````tallow```` which is obtained by cooking ````fat```` and is used in many recipes
new food item ````pemmican```` which requires tallow and other ingredients; very nutritious and lasts forever
new tool ````oil lamp```` which uses the new ````lamp oil```` liquid chemical to provide light
New items - particularly  ````tallow```` and  ````lamp oil```` - have been integrated into the existing recipes
New recipes for the new items


And it's not all for carnivores:
new recipe to extract cooking oil from plant-creature fluid sacs
new food item ````granola```` for all you bunny-hugging vegans out there, it's sort of like vegetarian pemmican

And numerous other typo fixes and corrections.

Thread: http://smf.cataclysmdda.com/index.php?topic=5168.msg83391