[Reorganize docs of functions]

[jtlap]

After adding new complex implementations of many math functions, I wonder if the doc structure of functions could not be changed in three parts :

1. functions that are not to be extended to any type other than wide or logical where of a fundamental type
2. functions requiring ordered types
3. functions that are or will potentially be extended to complex

These parts being divided if necessary to things as arithmetic trigonometry bit_wise etc.

In fact it seems to me this kind of subdivision is more sensible for users, but I am not sure.
What do you think of that ? Can you give pro and con and suggestions to improve the pattern if you think it is not stupid.
Perhaps this must wait until a new good concept hierarchy is filled into functions implementations?

[jfalcou]

complex has been moved tot heir own library solvign this particular issue