Replace clever join/split code with a straightforward loop.

On first reading, it's at all clear why one would join a new array with
commas only to split them by commas again.

It's clever idiom to initialize an array to empty strings, but an
old-fashioned simply for loop more clearly expresses the intent of the
code.
Merge pull request #18 from markstos/clarify-pool-logic

Replace clever join/split code with a straightforward loop.