Use of `sires` vs `candidate sires` vs `males`

[Foggalong]

Describe the problem or request
@gregorgorjanc has flagged in Foggalong/Robust-OCS-paper#2 that our using sires to refer to male candidates isn't quite accurate. Sires and dams are specifically selected males and females respectively.

Screenshots
This is primarily an issue with documentation, in places like

Each row of the file has an integer index of a candidate in the first column and a string for the sex of that candidate in the second column. Male candidates (sires) are denoted by an M and female candidates (dams) are denoted by an F.

but there are some changes needed for code also in places like

# define the M so that column i is [1;0] if i is a sire and [0;1] otherwise
M[0, sires] = 1
M[1, dams] = 1

Additional context
The fix for this will either involve switching S/D to M/F and updating language to talk about candidate males and females or (preferably, given its lighter diff) updating the language to talk about 'candidate sires' and 'candidate dams' as distinct from '(selected) sires' and '(selected) dams'.