Fix radius and coord order

Well, this was a weird one.
While the solar terminator appeared correct, the radius of the circle and the calculation of the antipode weren’t. I had a closer look and watched the terminator over a few minutes. It slowly moved eastwards.

LGeodesy.circle was passed half the area of a circle instead of a quarter of the circumference.
The antipode function is (lon, lat) so I simply reversed the order of the coordinates after calling it.

![fixed](https://cloud.githubusercontent.com/assets/614874/3739735/d675bcac-174d-11e4-98ac-7162fe2dfa6f.png)

Worked for me with leaflet-geodesy 0.2.0 and 0.2.1.