updated this library to support measuring not only from two distances but for multiple points.
commented the code as well

added two new options, so the developer can choose to show the total distance or partial distance or both.
figured out that this line is not needed, but I need to do more tests before I remove it
updated the measuring tool example so also show the new options

also, made it so each of the buttons have to be clicked individually, that is, the user should not be able to have to options clicked at the same time (it wil work but will make it very confusing to the user).
removed a line which was not needed and it also calls a non existing method
reported by zaczheng