+ Lens.recur_root for recursive lenses that also focus on the to item

~ Fix missing typespec on Lens.into

~ Elixir requirement set to 1.5

+ Lens now exports formatter settings to make deflens(p) behave like def(p)

+ Add Lens.put as Lens-first alternative to Kernel.put_in

+ Add Lens.filter/1 for defining aliases for filters with deflens

+ Add Lens.either as fallback for empty lens and upsert behaviour

- Remove get as it was easy to create bugs with it

+ Add Lens.one! to both fetch a single element and assert that there is only one
+ Add Lens.context for fetching {context, part} pairs

~ Lens.satisfy is deprecated

~ Lens.filter does what satisfy used to do. Use Lens.all |> Lens.filter to emulate the old behavior
+ Lens.reject as a counterpart to Lens.filter
+ Lens.key?/Lens.keys? that ignore missing keys

~ Make the values returned from `recur` follow the part -> whole pattern

+ Lens.map_keys and Lens.map_values for working with maps

~ Fix warnings on Elixir 1.4.0

+ Lens.const for defining lenses that always focus on the same value

+ Lens.into for lenses that can collect into a specific Collectable on update

+ deflensp for easily defining private lenses

+ Lens.back for focusing after the end of a list
+ Lens.front for focusing before the beginning of a list
+ Lens.behind for focusing after an element in a list
+ Lens.before for focusing before an element in a list
+ Lens.multiple for combining many lenses
+ Lens.indices for focusing on many indices at once