Added comments

If you like it.

I also though about Units, e.g. there is Modelica.SIunits.TimeAging for alpha and gamma, but no specific TimeAging for beta and delta.
Added comments
Removed start values since they are not required here.

Please double-check!
Added comments
Fix damping term
Fix units
Fix units
Fix dimension of cross
Add skew-symmetric to skew
Fix typo: increases -> decreases
Fix additional typo on increases -> decreases
Merge pull request #147 from michael-okeefe/mpo-2014-04-26

Review 2014-04-26
Removes superfluous default annotations. (no change in line numbers)
Removes superfluous default annotations. (includes updates in text refs)
Merge pull request #149 from dietmarw/removeDefaultAnnotations

Remove default annotations
Merge pull request #143 from tbeu/patch-skew

Add skew-symmetric to skew
Merge pull request #142 from tbeu/patch-cross

Fix dimension of cross
Merge pull request #141 from tbeu/patch-units

Fix rotational units
Merge pull request #117 from tbeu/patch-8

Fix damping term
Adding suggestion from #89