inline docs

[John Levon]

The attached is an unfinished patch that adds some
inline docs to tabular.h. Juergen/anyone, I would really
like suggestiong for the FIXMEs there (I get some of them
but am not 100% sure). Also please sanity check the comments
I added.

It also clarifies a couple of little things.

thanks
john

-- 
"To live outside the law you must be honest."
        - Bob Dylan

tabulardoc.diff.gz