takes exactly 1 argument (board) returns array with solution or throws an error, if board doesn't meet all conditions

• Function only takes a two-dimensional array of integers in range [1, 1000].
• The numbers of columns and rows in array have to be in range [3, 50].
• If there are three or more of the same integers adjacent vertically or horizontally, they are "removed" them from the board.
• Removed integers are represented by the value 0. If an empty space has integers on top of itself, integers "drop" until they hit a non-zero value on the very bottom of the board.
• The function compares adjacent integers, until there are no integers left to be removed. After that, a solved board is returned.

• Before looking for solution, we first check, if passed board meets the requirements: board is an array, array dimentions are OK and all elements are integers in range of [1,1000]
• A copy of the board is created: tmpBoard, so that we can avoid applying changes to original array in case one integer is used in both vertical and horizontal match
• When we enter the while loop, arrayChanged is set to false, so that if no changes are made during iteration, program will exit the loop
• Next we search columns for the same integers adjacent vertically:
  • we compare adjacent integers, if they're the same and different than 0, we compare next integer, until they're different, equal to 0 or board ends
  • if 3 or more adjacent integers of the same value are found, those integers are replaced with 0, but only in the tmpBoard array. arrayChanged is set to true, in order to search for new possibilities in next while loop iteration. Program then skips "tiles", that were set to 0. If less than 3 integers have the same value, we move onto the next tile.
  • When program finds a 0 or gets to less than 3 tiles away from border, it moves onto the next column
• In the next step the same algorithm is performed on rows of the board.
• Subsequently the changes from tmpBoard are reflected onto the board. First board gets filled with 0, then tmpArray is vertically "split" into n one-dimentional arrays called col. From those arrays all the zeroes are filtered away and the remaining integers are put onto the bottom of board.
• As iteration of the loop is about to end the contents of board are copied into tmpBoard. If any changes were made (as indicated by arrayChanged), the while loop will continue and the board will be searched again.
• After the while loop ends a stable board is returned.