correct column headers hen both one_file_per_group and all_reductions_in_one_file are active

[Roland Haas]

the column labels were sorted the wrong way if both options were active (nesting of loops was wrong). The attached patches correct this and add test cases for all 4 combinations of one_file_per_group and all_reductions_in_one_file.

Keyword:

[Roland Haas]

ok to apply (notice the strange iterator construction for end_reduction which I used since list iterators do not support operator+).

[Erik Schnetter]

Please apply.

[Roland Haas]

applied.