Added intro to linked list tutorial

[JacobGa03]

Added "Linked List Basics" tutorial to the linked list section.

[jerrettl]

Okay I think I am done getting through everything whew! As before, this covers a really nice breadth of a lot of details and information!

All I have are more little details here and there to make it all as clear as possible for the reader. I remember back when seeing students in office hours and how important it was to get all the little terms and precision, especially when dealing with pointers. (AVL self-balancing algorithms were also a doozy in this regard.) There are other spots, but hopefully that gives a general idea of what I am thinking. Hopefully this wasn't too crazy, so same thing, comments from #62 and #67 apply here, and just real minor stuff throughout.

• This is completely a subjective thing, but for the diagrams I see everything is surrounded by a box. This is good for visuals, but I worry this may be a little confusing as it appears like everything is a node, when in some cases they aren't actually nodes. Like NULL has a box around it, but NULL doesn't represent a node like the others. Instead, it is just a value set on another node's ->next member. It may be worth considering whether simple pointer variables like tempHead get the same boxing as a full node structure as well, since this kind of looks like it's an extra node in the chain altogether.

• For readability, when the arrows start getting more complicated towards the end, you may consider using these Unicode box drawing characters. They're a bit of a pain in the neck to use, but can come out looking really cool!

[jerrettl]

Same as earlier, should this be a temporary node or a temporary pointer? Since we are working with these new concepts in linked lists, that distinction can be very important! (From experience as a TA you can never be too careful with thinking that a student will assume to know what you mean.)

[JacobGa03]

Perhaps for NULL we can just use an X like I used for the binary trees?