More split types... split-list, n-files-per
Adding two more dataset splitting types:
- split_list -- the base_dataset value is actually a list of datasets, and we need to split it on commas to get a list of the datasets to run for each submission. This can also be used to make a set of non-dataset jobs that need a different parameter, like energy levels for montecarlo. This will not declare a dataset for the launches, just pick it from the list.
- n_files_per(n) -- make a dataset of the base dataset "with offset n*i limit n" for the i-th submission, so we have n files per submission (with possibly the last one coming up short).
Also, make sure we have the dataset split types written up in the wiki and linked from the edit page.