library index not exactly in alphabetical order

[zygoloid]

emplace, deque
push_front, deque
push_back, deque

are randomly collated between

input_iterator_tag

and

insert_after, forward_list

[AlisdairM]

This seems to be a deliberate decision in creating those index entries as related to 'insert' - I stumbled over this when cleaning up other mis-sortings due to use of '\tcode' in:
#741

This happens to be the one mis-filing I chose not to fix, as the use of 'insert@' in the index entry appears intentional - although I don't think that idiom is repeated anywhere else, and I would be happy to fix this too.

[jensmaurer]

This particular issue is fixed.