Merge branch 'jc/string-list-split'

string_list_split*() family of functions have been extended to simplify common use cases. * jc/string-list-split: string-list: split-then-remove-empty can be done while splitting string-list: optionally omit empty string pieces in string_list_split*() diff: simplify parsing of diff.colormovedws string-list: optionally trim string pieces split by string_list_split*() string-list: unify string_list_split* functions string-list: align string_list_split() with its _in_place() counterpart string-list: report programming error with BUG