arrays

I feel like indexOf's optional second parameter: fromIndex, is an unsung hero.

It has saved me many times from having to slice an array before calling indexOf.

Would you consider a PR with an example using fromIndex?

• Cleanup the tests
• Move module-specific tests into their own modules
• Rename the test case functions as we do in benchmarks

This operations will be used to drop elements in the steam on the right of the given element

var elements = []int{10,12,7,41,5,6}
res:=koazee.StreamOf(elements).DropRight(12).Out().Val()
fmt.Println(res)

// [10,12]

Haddock supports that.