mockingbirdnest/Principia — pull request #29 by eggrobin (2014-05-07 16:41:36+00:00)
Title: Private coordinates

`coordinates_` is now a private member, `Multivector` is now a class, no friends needed (by implementing `left += right` as `left = left + right` rather than as a coordinate-wise `+=`, same for the other assignment operators).
Tests pass unmodified.