[phobos] RFC: units type for D

[Benjamin Shropshire]

I have offered up a library that supports statically encoding units in 
the type system so as to prevent unit errors (adding distance and time) 
and to enforce correct conversions all around.

http://d.puremagic.com/issues/show_bug.cgi?id=3725

I'm looking for comments: What's holding it back from inclusion? What 
would need to be improved? The API? Better comments? (I haven't tested 
it recently so; make it build again?)