Add a way to reduce redundant data upon insertion to the buffer

[tfoote]

This is a refiling of ros/geometry#40 now that the buffer implementation is in this repository.

When new data is received if the most recent 3 data values are identical then the middle value is redundant as it can be reproduced via interpolation. Thus the middle value can be dropped as it's redundant to keep the linked list shorter.

Although in the generic moving frames this is uncommon. There are often frames that move sometimes but otherwise are static (and numerically identical which will make the interpolation also identical) and this could compress the data significantly and allow faster lookups.