backbone.shard: update copyright years

tests: move some test to another, more appropriate, section Too many methods that allow searching/filtering were put into "basic" category.

docs: reword overview and usage a bit

backbone.shard: add new methods (from Underscore), test them Namely, these methods are added: - difference - findIndex - findLastIndex - includes - sample

backbone.shard: add indexBy method, test it

docs: update test link to use HTTPS

test: remove trailing spaces

tests: update test page to use newer libs, HTTPS with SRI

backbone.shard: update license header

backbone.shard: strip trailing spaces