Added new bottom alignment options for the tooltip.

This commit contains some changes to allow greater control over the alignment of the tooltip when it's aligned to the bottom. It introduces three new values for the tooltipPosition option:

- 'bottom-right-align': aligns the tooltip to the right edge of the target element and move the tooltip arrow to the right side of the tooltip box.
- 'bottom-middle-align": aligns the center of the tooltip box with the center of the target element. The tooltip arrow is placed in the middle of the box.
- 'bottom-left-align': mainly for concistency. It aligns the tooltip to the left edge of the target element. Same as simply setting 'bottom'.