Skeleton.
double, not Scalar
It compiles, let's go shopping!
Testing.
Lint.
After egg's review.
Merge pull request #312 from pleroy/Matrix

Basic support for 3x3 matrices.  No usage in client code yet.
Orthogonalize.
Test.
Lint.
Merge pull request #313 from pleroy/GramSchmidt

Support for orthogonalization of two R3Elements.
Merge remote-tracking branch 'la-vache/master' into histories-are-synchronized
fix broken test.