refactoring, new stone type, faster delay

A lot of refactoring to compare it to the original version of the script to spot the bug with failed swaps.
sped up duration from 500 to 200 ms
changed board size for testing purposes
added test drop rates, although they aren't used currently
added common and uncommon test items
more renaming of GEM to Tile
moved moveTile() to below the main testing section (like the original)
added getRandRangeNum()