Use multiple alignment markers in chips

[eric-czech]

Newer chips have two markers, a circle and a cross, and eventually the extraction code should be able to use this to do rotation normalization as well as registration.

It is likely worth holding off on this though until one of two things happens:

• All experiments use dual marker chips
• There is a need for high-res captures that are magnified enough to only fit one apartment in an image

While it would be possible to support both types of chips in the same code, it will be a pain and an easier solution would likely be to tie off a branch of development for old chips and assume all new ones will have the two-marker design.