Adding `split_str_i` function to `array_utils`.

Also, adding associated tests to `check_array_utils.c`.
Updating `parse_summary_file` function.

Adding the parsing of an extra line containing the sample size
information for the means and standard deviations. This required
updating of `parse_summary_file` function in `parsing.c/h`.

Also, updating tests and test data accordingly.
Updating `eureject_main` function in `eureject.c`.

Adding the parsing and writing of samples sizes to summary files.
Fixing bug in `parse_summary_file`.

When I added parsing of sample sizes I introduced a bug. I was
closing the the file before parsing the last line with the sample
sizes. This commit fixes this problem.

Also, updating tests. The `parse_summary_file` tests were written
but never added to the test suite. Now they are added and get
run at check.
Updating `eureject_main.c` in `eureject.c`.

Adding the writing of sample sizes to stderr.