Fix other multiple correction methods than Bonferroni

[tjofas]

We discovered that multiple correction methods other than Bonferroni did not apply any corrections. After troubleshooting it was discovered that this is due to the dataframe with comparisons being sent row by row to the functions handling the corrections. Thus multipletests was only run for one p-value at a time.

This PR fixes this so that multipletests gets the p-values from all of the conducted comparisons and is able to do multiple corrections using the supported methods. Also updated tests to include verifying that the adjusted p-values are correct for other correction methods than Bonferroni.