* move 'remove' tests to separate file
* move 'repeat' tests to separate file
* move 'replace' tests to separate file
* move 'reverse' tests to separate file
* move 'scan' tests to separate file
* move 'set' tests to separate file
* move 'slice' tests to separate file
* move 'sort' tests to separate file
* move 'sortBy' tests to separate file
* move 'sortWith' tests to separate file
* move 'splitAt' tests to separate file
* move 'splitEvery' tests to separate file
* move 'splitWhen' tests to separate file
* move 'startsWith' tests to separate file
* move 'subtract' tests to separate file
* move 'sum' tests to separate file
* move 'symmetricDifference' tests to separate file
* move 'symmetricDifferenceWith' tests to separate file
* move 'tail' tests to separate file
* move 'take' tests to separate file