yearRange option relative to today's year returns a single year

[ericlanehart]

When setting the ​yearRange option to a range in the style of '-40:2', only a single year is returned in the dropdown menu enabled with changeYear. The year is the oldest year that would have otherwise been returned as an option. Changing the format to double digits doesn't have an effect. This bug seems to have been introduced in 1.4.0/1.8.0, as this option worked in 1.3.2/1.7.3.

Compare:

• ​http://jsbin.com/iquge3/edit

to:

• ​http://jsbin.com/acefo4/edit

[Scott González]

"-40:2" means all the years beween 40 years ago and the year 2. What you want is "-40:+2"