Cesium ghost sessions

[landswellsong]

Clearing the geolines with dotted parts leaves artifacts in Cesium. Assuming that the selection cuts the paths into 3 parts (dotted, red, dotted), here are my observations:

1. The leftover parts differ in indexes, one path may have the 0th part left whereas another path would have a 2th part left;
2. The leftover parts seem to be in the same direction respective to the selection (both up or both down);
3. The leftover parts respond to obj.show = true/false correctly.

For the purpose of #244 I'll put a workaround, but this needs to be eventually resolved. Myseterious stuff.