doc: Fold information from the memory model interlude in the tutorial elsewhere
s/moved variable/moved value/
Merge pull request #4440 from pcwalton/tutorial

doc: Fold information from the memory model interlude in the tutorial elsewhere
Merge pull request #4493 from jbclements/rename-moved-variable-to-moved-value

s/moved variable/moved value/
Minor cleanup and eliminate a bad copy
librustc: Implement write guards for borrowing `@mut` to `&` or `&mut`. r=nmatsakis
replace treemap with a balanced tree
add a lazy forward iterator to TreeMap
make Eq implementation O(n)
clean up equality code a bit
rm extra newline
remove 'TODO' from the list of future improvements
fix API of union
implement set difference
range search would be nice
add scaffolding for symmetric_difference/union
make TreeSet tests a bit more paranoid
implement set union
implement symmetric_difference
fix bug in union implementation (missing return)