Iterator/Vec examples

[moosingin3space]

• Iterate while appending, imperative
• Iterate while appending, functional
• Remove elements in-place
• Filter
• Borrowck concerns when passing Iterators around
• Accumulator pattern (fold)
• Demonstrate what flat_map means

If you can think of any more, leave them in the comments.

[cbreeden]

@moosingin3space I wrote a quick something that takes a reference to an iterator. I don't know if it does a good job explaining the inherent problems. Any ideas?

[moosingin3space]

@cbreeden I modified your example to show the problem I encountered while learning Rust. For some reason I don't have commit privileges, so I'll have to fork it.