Numerical stability

[mortonjt]

Right now - to convert between clr and alr coordinates, the alr coordinates are first converted to proportions, which are then clr transformed.

This is known to be numerically instable (because proportions suck).
The work around is to make the corresponding alr coordinate zero, then mean center those quantities -- that will get your clr transformed coordinates.

[mortonjt]

This is now done.