v4
Added `isFirstVisibleBar()` and `isLastVisibleBar()` functions to determine the first and last visible bar.
The functions are:
isFirstVisibleBar()
Condition to determine if a bar is the first visible bar.
Returns: (bool) True if the current bar is the first visible bar.
isLastVisibleBar()
Condition to determine if a bar is the last visible bar.
Returns: (bool) True if the current bar is the last visible bar.