Support more of the functions from guava iterables

[Anund McKague]

Iterables would be simpler to use if it had it's own copy of the guava iterables functions

* concat (concat(Iterable, Iterable) concat(Iterable, Iterable, Iterable) and so on)
* cycle
* find
* get getFirst getLast 
* indexOf
* partition
* remove/retain
* take/take while
* drop/drop while

[Anund McKague]

• find is replaced by findFirst
• take/drop/partition are already implemented
• remove/retain are just different names for filters
• get getFirst getLast indexOf can be maintained by guava

That leaves

• concat
• cycle
• take while
• drop while
• foldleft and foldright might be worth adding

[Anund McKague]

• elementsEqual(Iterable<?> iterable1, Iterable<?> iterable2) - Determines whether two iterables contain equal elements in the same order.
• filter(Iterable<?> unfiltered, Class<T> type)
• frequency(Iterable<?> iterable, Object element) - Returns the number of elements in the specified iterable that equal the specified object.
• toArray(Iterable<? extends T> iterable, Class<T> type) - Copies an iterable's elements into an array.

[Anund McKague]

I'm choosing not to implement the remaining duplicate methods for now. Folds should be brought up as a separate piece of work.