Change XY formatting on LCD (PR#2740)

According to #123 negative values for XY at or below -100 are displaying incorrectly, dropping the first digit. Deltas can easily have XY values in this range. This PR adds a function to display floats/ints formatted like `_123`, `-123`, `_-12`, or `__-1` as appropriate and applies it to the XY coordinates on Hitachi displays. It also moves the Z value to the right to be consistent with the XY formatting.