[Developers] (extract_) diagonal

[Arni Magnusson]

The current manuals for ADMB (p. 15-9) and AUTODIF (p. 4-11) describe a 
function 'extract_diagonal', but it seems to be implemented as 'diagonal'. 
To verify this, I used a slightly modified version of simple.tpl:

DATA_SECTION
   init_int n
   init_vector X(1,n)
   init_vector Y(1,n)
PARAMETER_SECTION
   init_number b0
   init_number b1
   vector Yfit(1,n)
   matrix foo(1,3,1,3)
   objective_function_value RSS
PRELIMINARY_CALCS_SECTION
   foo(1,1)=11; foo(1,2)=12; foo(1,3)=13;
   foo(2,1)=21; foo(2,2)=22; foo(2,3)=23;
   foo(3,1)=31; foo(3,2)=32; foo(3,3)=33;
PROCEDURE_SECTION
   Yfit = b0 + b1*X;
   RSS = norm2(Y-Yfit);
REPORT_SECTION
   report << diagonal(foo) << endl;

If you change 'diagonal' to 'extract_diagonal' the model does not compile. 
The function name should either be changed in the manuals, or in the 
source code.

Arni