Copy edit Lab/Tutorial 2

[50Wliu]

The copy/edit saga, now on Volume 2!

• A lot of hints have been added to the pre-lab.
• Because we've had complaints about the length of the lab writeup, I've went and done something about it: I've removed all the method explanations and moved them to the header files instead. Try complaining now! :P
• Superficial changes to the LLDB tutorial. Hopefully I've made -o a little less confusing.
• 1bc9b1a contains a very important change: it prevents a segfault when testing the copy constructor/operator=. It was inadvertently introduced in 8373a5a (ignore the one I linked in the commit description).
• Spacing adjustments to all the source files. ListTest is still ugly, but hopefully a little less so now.
• Changed line endings from CRLF to LF, since everyone will be working on Unix.
• Address/LeakSanitizer! This is dependent on llvm-symbolizer-6.0 being symlinked correctly on the VirtualBox image (and I need to check on macOS as well). Closes #28.

[50Wliu]

@adeet1 I'd like your thoughts on these changes, as you just took the course. Do you think it makes more sense and is easier to read through than before?