Style references to numbered lines in example code consistently

[Eelis]

The following two fragments are from [except.ctor]/2 and [temp.class.order]/2, respectively:

Note how the #1/#2 are in body font in the first, and in code font in the second.

(Also, the A/B/C/Din the second fragment should probably not be in code font.)

[jensmaurer]

We don't do #1 -style references very often, it seems, but where we have them, \tcode is the exception. We usually just have body font #1 references.

That suggests point-fixes for the few issues discovered above as opposed to broad harmonization.