added interval heap implementation and fixed immutslist test code (explicit borrowing)
simplified interval_heap_push + added name to Cargo.toml author list
Merge branch 'master'
intervalheap: more docs, style, add into_sorted_vec and test
Merge branch 'master' of https://github.com/Gankro/collect-rs
Merge pull request #1 from sellibitze/master

added interval heap implementation and fixed immutslist test code