fixed character sprite jitter when panning the tilemap

Fixed by making the primary character model invisible and creating a
visible sprite to follow the character model, but whose position is
rounded down from the model's more precise position.
Revert "fixed character sprite jitter when panning the tilemap"

This reverts commit f91503b904d9d513e01fb7cec871d8c3bdc5832d.
Revert "Revert "fixed character sprite jitter when panning the tilemap""

This reverts commit 041c52d04c6397c30ab7b569bf2def1a018b41be.