[first checked in
waterson@maubi.net**20080319154507] 
[follow library hierarchy
waterson@maubi.net**20080319155321] 
[fix module name
waterson@maubi.net**20080319155429] 
[start writing docs
waterson@maubi.net**20080319172020] 
[generalize float to any real type, scale correctly
waterson@maubi.net**20080402232724]