Change ol.TileCoord to Array.<number>

This PR changes the `ol.TileCoord` type to an array of three numbers: `[z, x, y]`. This is as discussed in #2514.

I did not test every example. I would be good that someone else could also test some of the examples. Thanks.

Closes #2514.
should be:
```
tmpTileCoord[0] = tileCoord[0];
tmpTileCoord[1] = x;
tmpTileCoord[2] = tileCoord[2];
```