| position | The target position to insert at. | 
| insertCells | The number of columns, rows or layers of cells to insert. | 
Inserts cells into the Tilemap.
| position | The target position to insert at. | 
| numColumns | The number of columns to insert. | 
| numRows | The number of rows to insert. | 
| numLayers | The number of layers of cells to insert. | 
Inserts cells into the Tilemap.